JP2023044620A - Active material, negative electrode layer, battery, and manufacturing method thereof - Google Patents

Abstract

To provide an active material whose volume change is small due to charging and discharging.SOLUTION: An active material according to the present disclosure has a silicon clathrate type II crystal phase, has voids inside the primary particles, and has a pore diameter of 100 nm or less, void volume A of the voids is greater than 0.15 cc/g and 0.40 cc/g or less.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to active materials, negative electrode layers, batteries, and methods of making the same.

Batteries have been actively developed in recent years. For example, the automotive industry is developing batteries for use in electric vehicles (BEV) or hybrid vehicles (HEV). Also, Si is known as an active material used in batteries.

For example, Patent Document 1 discloses an all-solid battery system containing alloy-based negative electrode active material particles such as silicon particles. On the other hand, Patent Document 2 discloses that it is possible to use silicon clathrate as a negative electrode active material of a lithium ion battery from a calculation point of view. Further, Patent Documents 3 and 4 disclose an active material having a silicon clathrate II crystal phase and voids inside primary particles.

JP 2017-059534 A U.S. Patent Application Publication No. 2012/0021283 Japanese Patent Application Laid-Open No. 2021-158003 JP 2021-158004 A

Si has a large theoretical capacity and is effective in increasing the energy density of batteries. On the other hand, Si undergoes a large change in volume during charging and discharging.

The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide an active material whose volume change is small due to charging and discharging.

[1]
It has a silicon clathrate type II crystal phase, has voids inside the primary particles, and has a pore diameter of 100 nm or less. g or less, the active material.

[2]
It has a silicon clathrate type II crystal phase, has voids inside the primary particles, and has a pore diameter of 50 nm or less, and the void volume B of the voids is greater than 0.065 cc/g and 0.25 cc/g. g or less, the active material.

[3]
The active material according to [2], wherein the void volume A of the voids having a pore diameter of 100 nm or less is 0.05 cc/g or more and 0.40 cc/g or less.

[4]
In X-ray diffraction measurement using CuKα rays, peak A located at 2θ = 20.09° ± 0.50° and 2θ = 31.72° ± A peak B located at 0.50° was observed, the intensity of the peak A was I _A , the intensity of the peak B was I _B , and the maximum intensity at 2θ = 22 ° to 23 ° was I _M. In any case, I _A /I _M is 1.75 or more and 2.00 or less, and I _B /I _M is 1.35 or more and 1.75 or less, according to any one of [1] to [3] active material.

[5]
A negative electrode layer containing the active material according to any one of [1] to [4].

[6]
A battery comprising a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the negative electrode layer is the negative electrode layer according to [5].

[7]
The method for producing an active material according to any one of [1] to [4], comprising: an alloying step of reacting a Na source and a Si source to obtain a Na—Si alloy; and heating the Na—Si alloy. a silicon clathrate forming step of reducing the amount of Na in the Na—Si alloy to form a silicon clathrate II type crystal phase, wherein the silicon clathrate forming step includes: Using a scavenger that captures Na in the active A method of making a substance.

[8]
A method for producing a negative electrode layer, comprising: an active material producing step of producing an active material by the method for producing an active material according to [7]; and a negative electrode layer forming step of forming a negative electrode layer using the active material.

[9]
The negative electrode layer forming step includes a press process for pressing the negative electrode layer in the thickness direction, and the press process reduces the void volume D of the voids having a pore diameter of 50 nm or less in the active material to 0. 0.035 cc/g or more and 0.11 cc/g or less.

[10]
The negative electrode layer according to [9], wherein the press treatment sets the void volume E of the voids having a pore diameter of 100 nm or less in the active material to 0.053 cc/g or more and 0.16 cc/g or less. manufacturing method.

[11]
A method for manufacturing a battery, comprising: an active material manufacturing step of manufacturing an active material by the method of manufacturing an active material according to [7]; and a negative electrode layer forming step of forming a negative electrode layer using the active material.

The present disclosure has the effect of being able to obtain an active material with a small volume change due to charging and discharging.

It is a schematic perspective view explaining the crystal phase of Si. 1 is a schematic cross-sectional view illustrating a battery in the present disclosure; FIG. 4 is a flow chart illustrating a method for manufacturing an active material in the present disclosure; 1 shows the results of XRD measurement for active materials obtained in Examples 1 to 3 and Comparative Example 1. FIG.

Hereinafter, the active material, the negative electrode layer, the battery, and the manufacturing method thereof according to the present disclosure will be described in detail.

A. Active material The active material in the present disclosure has a silicon clathrate II crystal phase, has voids inside the primary particles, and has a pore diameter of 100 nm or less. is 50 nm or less, the void amount B is large.

The active material in the present disclosure has a silicon clathrate II crystal phase. As shown in FIG. 1(a), in the silicon clathrate type II crystal phase, a plurality of Si elements form a polyhedron (cage) containing pentagons or hexagons. This polyhedron has internal spaces that can contain metal ions such as Li ions. By inserting metal ions into this space, volume change due to charging and discharging can be suppressed. In particular, in all-solid-state batteries, it is generally necessary to apply a high confining pressure in order to suppress volume changes due to charging and discharging, but by using the active material in the present disclosure, it is possible to reduce the confining pressure. As a result, it is possible to suppress an increase in the size of the restraint jig.

On the other hand, ordinary Si has a diamond-type crystal phase. As shown in FIG. 1B, in the diamond-shaped Si crystal phase, tetrahedrons are formed by a plurality of Si elements. Since the tetrahedron does not have a space inside which can contain metal ions such as Li ions, it is difficult to suppress volume change due to charging and discharging. Therefore, durability tends to deteriorate.

In addition, the active material in the present disclosure has voids inside the primary particles. As described above, the silicon clathrate type II crystal phase has a cage capable of enclosing metal ions such as Li ions, and therefore can suppress volume change due to charging and discharging. If the primary particles having the crystal phase have voids inside, the voids also contribute to the suppression of volume change, so that the volume change due to charging and discharging can be further suppressed. In addition, the active material according to the present disclosure has many microvoids with a pore diameter of 100 nm or less, or many microvoids with a pore diameter of 50 nm or less. Therefore, the volume change due to charge/discharge can be uniformly mitigated. Furthermore, since there are many minute voids, crushing of the voids by pressing can be suppressed. In particular, by adopting the manufacturing method described later, the void volume A of fine voids with a pore diameter of 100 nm or less or the void volume B of fine voids with a pore diameter of 50 nm or less is increased.

The active material in the present disclosure has a silicon clathrate II crystal phase. The crystalline phase of silicon clathrate type II usually belongs to the space group (Fd-3m). The crystal phase of the silicon clathrate type II has 2θ=20.09°, 21.00°, 26.51°, 31.72°, 36.26°, 53.0° in X-ray diffraction measurement using CuKα rays. It has a typical peak at 01°. These peak positions may vary within a range of ±0.50°, may vary within a range of ±0.30°, and may vary within a range of ±0.10°. good too.

The active material in the present disclosure preferably has a silicon clathrate II crystal phase as a main phase. "Having a silicon clathrate type II crystal phase as a main phase" means that the peak belonging to the silicon clathrate type II crystal phase has the highest diffraction intensity among the peaks observed by X-ray diffraction measurement. It means that The definition of "main phase" is the same for other crystal phases.

In the silicon clathrate type II crystal phase, the peak located at 2θ = 20.09° ± 0.50° is defined as peak A, and the peak located at 2θ = 31.72° ± 0.50° is defined as peak B. . Further, the intensity of peak A is defined as _IA , and the intensity of peak B is defined as _IB . On the other hand, the maximum intensity at 2θ=22° to 23° is defined as _IM . 2θ=22° to 23° is a range in which the peak of the crystal phase related to Si usually does not appear, so it can be used as a reference.

The value of I _A /I _M is preferably greater than one. When the value of I _A /I _M is 1 or less, it can be determined that the crystal phase of silicon clathrate II type is not substantially formed. The value of I _A /I _M is, for example, 1.75 or more, and may be 1.80 or more. On the other hand, the value of I _A /I _M is, for example, 10 or less, may be 5 or less, may be 2.00 or less, or may be 1.95 or less.

The value of I _B /I _M is preferably greater than one. When the value of I _B /I _M is 1 or less, it can be determined that the silicon clathrate II type crystal phase is not substantially formed. The value of I _B /I _M is, for example, 1.35 or more, may be 1.40 or more, or may be 1.45 or more. On the other hand, the value of I _B /I _M is, for example, 7 or less, may be 4 or less, may be 1.75 or less, or may be 1.70 or less.

In addition, the active material in the present disclosure preferably does not have a diamond-shaped Si crystal phase, but may have a small amount. The diamond-shaped Si crystal phase is typically located at 2θ = 28.44°, 47.31°, 56.10°, 69.17°, and 76.37° in X-ray diffraction measurement using CuKα rays. peak. These peak positions may vary within a range of ±0.50°, may vary within a range of ±0.30°, and may vary within a range of ±0.10°. good too.

When peak C located at 2θ=28.44°±0.50° is observed as a peak of the diamond-shaped Si crystal phase, the intensity of peak _C is defined as IC. I _A /I _C is, for example, greater than 1, may be 1.5 or more, may be 2 or more, or may be 3 or more. The preferred range of _IB / _IC is the same as the preferred range of _IA / _IC .

The active material in the present disclosure preferably does not have a silicon clathrate I type crystal phase. The crystalline phase of silicon clathrate type I usually belongs to the space group (Pm-3n). The crystal phase of the silicon clathrate type I has 2θ=19.44°, 21.32°, 30.33°, 31.60°, 32.82°, 36.0° in X-ray diffraction measurement using CuKα rays. It has typical peaks at 29°, 52.39° and 55.49°. These peak positions may vary within a range of ±0.50°, may vary within a range of ±0.30°, and may vary within a range of ±0.10°. good too. "Not having a crystalline phase" can be confirmed by confirming no peak of the crystalline phase in the X-ray diffraction measurement.

Examples of the shape of the active material in the present disclosure include particulate. The active material may be primary particles or secondary particles obtained by agglomeration of primary particles. In either case, the primary particles usually have voids inside.

The active material in the present disclosure preferably has many fine voids with pore diameters of 100 nm or less. The void volume (accumulated pore volume) A of voids having a pore diameter of 100 nm or less is, for example, 0.05 cc/g or more, may be 0.07 cc/g or more, or may be 0.10 cc/g or more. It may be 0.12 cc/g or more. Moreover, the void amount A may be, for example, greater than 0.12 cc/g, or may be greater than 0.15 cc/g. On the other hand, the void amount A is, for example, 0.40 cc/g or less, may be 0.39 cc/g or less, may be 0.35 cc/g or less, or may be 0.30 cc/g or less. 0.25 cc/g or less, 0.24 cc/g or less, or 0.23 cc/g or less. The void amount A can be determined by, for example, mercury porosimeter measurement, BET measurement, gas adsorption method, 3D-SEM, and 3D-TEM. The method for measuring void amounts other than the void amount A is the same.

The active material in the present disclosure preferably has many fine voids with pore diameters of 50 nm or less. Voids with a pore diameter of 50 nm or less can further suppress crushing of the voids by pressing, compared to voids with a pore diameter of greater than 50 nm and 100 nm or less. The void volume B of voids having a pore diameter of 50 nm or less is, for example, 0.05 cc/g or more, may be greater than 0.065 cc/g, may be 0.072 cc/g or more, or may be 0.072 cc/g or more. It may be 10 cc/g or more, 0.105 cc/g or more, 0.11 cc/g or more, or 0.15 cc/g or more. On the other hand, the void amount B is, for example, 0.25 cc/g or less, may be 0.22 cc/g or less, may be 0.17 cc/g or less, or may be 0.165 cc/g or less. may be 0.16 cc/g or less.

The active material in the present disclosure preferably has many fine voids with pore diameters of 10 nm or less. Voids with a pore diameter of 10 nm or less can accommodate the precipitated Li at a higher filling rate than voids with a pore diameter of greater than 10 nm and a pore diameter of 50 nm or less, so the confining pressure increases. can be reduced. The void volume X of voids having a pore diameter of 10 nm or less is, for example, 0.015 cc/g or more, may be 0.0167 cc/g or more, may be 0.020 cc/g or more, or may be 0 It may be 0.023 cc/g or more. On the other hand, the void amount X is, for example, 0.09 cc/g or less. In addition, the void amount X may be 0.0337 cc/g or less.

The active material in the present disclosure has voids inside the primary particles. The porosity is, for example, 4% or more, and may be 10% or more. Moreover, the porosity is, for example, 40% or less, and may be 20% or less. The porosity can be obtained, for example, by the following procedure. First, an electrode layer containing an active material is cross-sectioned by ion milling. Then, a photograph of the particles is obtained by observing the cross section with an SEM (scanning electron microscope). Using image analysis software from the obtained photograph, the silicon portion and the void portion are sharply distinguished and binarized. The areas of the silicon portion and the void portion are obtained, and the porosity (%) is calculated from the following formula.
Porosity (%) = 100 x (area of void)/((area of silicon portion) + (area of void))

Specific image analysis and porosity calculation can be performed as follows. As image analysis software, for example, Fiji ImageJ bundled with Java 1.8.0_172 (hereafter Fiji) is used. A secondary electron image and a backscattered electron image in the same field of view are synthesized to form an RGB color image. The resulting RGB image is then blurred by the function "Median (filter size=2)" in Fiji to remove pixel-by-pixel noise. Next, using Fiji, the silicon part and the void part in the SEM image are separately painted, and the void amount is calculated from the area ratio of the silicon part and the void part.

In RGB color imaging, both the secondary electron image and the backscattered electron image are represented in gray scale. Similarly, the brightness y is assigned to the Green value. As a result, for example, each pixel is converted into an RGB image with R=x, G=y, and B=(x+y)/2.

The average particle size (D ₅₀ ) of the primary particles is, for example, 50 nm or more, may be 100 nm or more, or may be 150 nm or more. On the other hand, the average particle diameter ( _D50 ) of the primary particles is, for example, 3000 nm or less, may be 1500 nm or less, or may be 1000 nm or less. Further, the average particle diameter ( _D50 ) of the secondary particles is, for example, 1 μm or more, may be 2 μm or more, or may be 5 μm or more. On the other hand, the average particle size (D ₅₀ ) of secondary particles is, for example, 60 μm or less, and may be 40 μm or less. The average particle size (D ₅₀ ) can be determined by observation with SEM, for example. The number of samples is preferably large, for example, 20 or more, may be 50 or more, or may be 100 or more.

Although the composition of the active material in the present disclosure is not particularly limited, it is preferably represented by Na _x Si ₁₃₆ (0≦x≦24). x may be 0 or greater than 0. On the other hand, x may be 20 or less, 10 or less, or 5 or less. Note that the active material in the present disclosure may contain an unavoidable component (eg, Li). The composition of the active material can be determined, for example, by EDX, XRD, XRF, ICP, atomic absorption spectroscopy. Compositions of other compounds can be similarly measured. Note that an unavoidable oxide film is generally formed on the surface of the active material. Therefore, the active material may contain a small amount of O (oxygen). In addition, the active material may contain a trace amount of C (carbon) derived from the manufacturing process.

Active materials in the present disclosure are typically used in batteries. The active material in the present disclosure may be a negative electrode active material or a positive electrode active material, but the former is preferred. The present disclosure can also provide an electrode layer (negative electrode layer or positive electrode layer) having the active material described above and a battery having the electrode layer. Examples of the method for producing the active material include the production method described later in "D. Production method for active material".

B. Negative Electrode Layer The negative electrode layer in the present disclosure contains the active material described above.

According to the present disclosure, by using the active material described above, the negative electrode layer can have a small volume change due to charging and discharging.

The negative electrode layer is a layer containing at least a negative electrode active material. The description of the negative electrode active material is omitted here because it is the same as described in the above "A. Active material". When the negative electrode layer is manufactured by press treatment, voids existing inside the primary particles of the negative electrode active material may be crushed. The negative electrode active material contained in the negative electrode layer may have a void amount D and a void amount E described later within a predetermined range. The proportion of the negative electrode active material in the negative electrode layer is, for example, 20% by weight or more, may be 30% by weight or more, or may be 40% by weight or more. If the ratio of the negative electrode active material is too small, there is a possibility that sufficient energy density cannot be obtained. On the other hand, the proportion of the negative electrode active material is, for example, 80% by weight or less, may be 70% by weight or less, or may be 60% by weight or less. If the ratio of the negative electrode active material is too high, the ionic conductivity and electronic conductivity of the negative electrode layer may relatively decrease.

The negative electrode layer may contain at least one of an electrolyte, a conductive material and a binder, if necessary. Examples of the electrolyte include electrolytes described later in "C. Battery 3. Electrolyte layer". Examples of conductive materials include carbon materials, metal particles, and conductive polymers. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fibers, carbon nanotubes (CNT), and carbon nanofibers (CNF). . Examples of binders include rubber-based binders and fluoride-based binders.

The thickness of the negative electrode layer is, for example, 0.1 μm or more and 1000 μm or less. Anode layers in the present disclosure are typically used in batteries.

C. Battery FIG. 2 is a schematic cross-sectional view illustrating a battery in the present disclosure. A battery 10 shown in FIG. , and a negative electrode current collector 5 for collecting current of the negative electrode layer 2 . In the present disclosure, the negative electrode layer 2 is the negative electrode layer described in "B. Negative electrode layer" above.

According to the present disclosure, by using the negative electrode layer described above, it is possible to obtain a battery with small volume change due to charging and discharging.

1. Negative Electrode Layer The negative electrode layer in the present disclosure is the same as described in "B. Negative Electrode Layer" above, so description thereof is omitted here.

2. Positive Electrode Layer The positive electrode layer is a layer containing at least a positive electrode active material. Moreover, the positive electrode layer may contain at least one of an electrolyte, a conductive material, and a binder, if necessary.

Examples of positive electrode active materials include oxide active materials. Examples of oxide active materials include rock salt layered active materials such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , LiVO ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiMn ₂ O ₄ and Li ₄ . Spinel-type active materials such as Ti ₅ O ₁₂ and Li(Ni _0.5 Mn _1.5 )O ₄ and olivine-type active materials such as LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ and LiCoPO ₄ can be used.

A coating layer containing a Li ion conductive oxide may be formed on the surface of the oxide active material. This is because the reaction between the oxide active material and the solid electrolyte (especially the sulfide solid electrolyte) can be suppressed. Li-ion conductive oxides include, for example, LiNbO ₃ . The thickness of the coat layer is, for example, 1 nm or more and 30 nm or less. Moreover, _Li2S can also be used as a positive electrode active material, for example.

Examples of the shape of the positive electrode active material include particulate. The average particle size (D ₅₀ ) of the positive electrode active material is not particularly limited, but is, for example, 10 nm or more, and may be 100 nm or more. On the other hand, the average particle size (D ₅₀ ) of the positive electrode active material is, for example, 50 μm or less, and may be 20 μm or less. The average particle size (D ₅₀ ) can be calculated, for example, from measurements using a laser diffraction particle size distribution meter and a scanning electron microscope (SEM).

The electrolyte, conductive material, and binder used in the positive electrode layer are the same as those described in "B. Negative electrode layer" above, and therefore descriptions thereof are omitted here. The thickness of the positive electrode layer is, for example, 0.1 μm or more and 1000 μm or less.

3. Electrolyte Layer The electrolyte layer is a layer formed between the positive electrode layer and the negative electrode layer and contains at least an electrolyte. The electrolyte may be a solid electrolyte or a liquid electrolyte (electrolytic solution).

Solid electrolytes include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes and halide solid electrolytes, and organic polymer electrolytes such as polymer electrolytes. Examples of sulfide solid electrolytes include Li element, X element (X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S element. and solid electrolytes. Moreover, the sulfide solid electrolyte may further contain at least one of the O element and the halogen element. Halogen elements include, for example, F element, Cl element, Br element, and I element. The sulfide solid electrolyte may be glass (amorphous) or glass ceramics. Examples of sulfide solid electrolytes include Li ₂ SP ₂ S ₅ , LiI-Li ₂ SP ₂ S ₅ , LiI-LiBr-Li ₂ SP ₂ S ₅ , Li ₂ S-SiS ₂ , Li ₂ S—GeS ₂ and Li ₂ SP ₂ S ₅ —GeS ₂ .

The electrolytic solution preferably contains a supporting salt and a solvent. Examples of the supporting salt (lithium salt) of the electrolytic solution having lithium ion conductivity include inorganic lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ , LiCF ₃ SO ₃ and LiN(CF ₃ SO ₂ ) _{2 .} , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(FSO ₂ ) ₂ , LiC(CF ₃ SO ₂ ) ₃ and the like. Solvents used in the electrolytic solution include, for example, ethylene carbonate (EC), propylene carbonate (PC), cyclic esters (cyclic carbonates) such as butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl Examples include chain esters (chain carbonates) such as methyl carbonate (EMC). The electrolytic solution preferably contains two or more solvents.

The thickness of the electrolyte layer is, for example, 0.1 μm or more and 1000 μm or less.

4. Other Configurations The battery in the present disclosure preferably has a positive electrode current collector that collects current for the positive electrode layer and a negative electrode current collector that collects current for the negative electrode layer. Examples of materials for the positive electrode current collector include SUS, aluminum, nickel, iron, titanium and carbon. On the other hand, examples of materials for the negative electrode current collector include SUS, copper, nickel and carbon.

The battery according to the present disclosure may further include a restraining jig that applies a restraining pressure along the thickness direction to the positive electrode layer, the electrolyte layer, and the negative electrode layer. In particular, when the electrolyte layer is a solid electrolyte layer, it is preferable to apply a confining pressure in order to form good ion-conducting paths and electron-conducting paths. The confining pressure is, for example, 0.1 MPa or more, may be 1 MPa or more, or may be 5 MPa or more. On the other hand, the confining pressure is, for example, 100 MPa or less, may be 50 MPa or less, or may be 20 MPa or less.

5. Battery The type of battery in the present disclosure is not particularly limited, but is typically a lithium ion battery. Also, the battery in the present disclosure may be a liquid battery containing an electrolytic solution as an electrolyte layer, or an all-solid battery having a solid electrolyte layer as an electrolyte layer. Also, the battery in the present disclosure may be a primary battery or a secondary battery, but is preferably a secondary battery. This is because they can be repeatedly charged and discharged, and are useful, for example, as batteries for vehicles.

A battery in the present disclosure may be a single cell or a stacked battery. The laminated battery may be a monopolar laminated battery (parallel connected laminated battery) or a bipolar laminated battery (series connected laminated battery). Examples of the shape of the battery include coin type, laminate type, cylindrical type, and square type.

D. Method for Manufacturing Active Material FIG. 3 is a flowchart illustrating a method for manufacturing an active material in the present disclosure. In the manufacturing method shown in FIG. 3, first, a Na source and a Si source are reacted to obtain an Na—Si alloy (alloying step). At this time, as the Si source, particles having a large void volume C of pores having a pore diameter of 50 nm or less are used. Next, the Na--Si alloy is heated to reduce the amount of Na in the Na--Si alloy to form a silicon clathrate II type crystal phase (silicon clathrate formation step). At this time, a trapping agent that traps Na in the Na—Si alloy is used. As a result, an active material is obtained in which at least one of the void amount A and the void amount B is within a predetermined range and has a silicon clathrate II type crystal phase.

According to the present disclosure, by using a predetermined Si source in the alloying step and further using a predetermined scavenger in the silicon clathrate formation step, an active material with small volume change due to charging and discharging can be obtained.

1. Alloying Step The alloying step in the present disclosure is a step of reacting a Na source and a Si source to obtain a Na—Si alloy. In the alloying step, particles having a void volume C of pores having a pore diameter of 50 nm or less of 0.02 cc/g or more and 0.20 cc/g or less are used as the Si source.

The Si source is particles containing at least Si. The Si source may be Si alone or an alloy of Si and other metals. When the Si source is an alloy, the alloy preferably contains Si as a main component. The proportion of Si in the alloy is, for example, 50 at % or more, may be 70 at % or more, or may be 90 at % or more.

The Si source is preferably porous Si having many voids inside the primary particles. In the Si source, the void volume C of pores having a pore diameter of 50 nm or less is usually 0.02 cc/g or more, may be 0.05 cc/g or more, or is 0.10 cc/g or more. 0.11 cc/g or more, or 0.12 cc/g or more. On the other hand, the void volume C is usually 0.20 cc/g or less, and may be 0.19 cc/g or less. Also, the BET specific surface area of the Si source is, for example, 20 m ² /g or more, may be 25 m ² /g or more, or may be 30 m ² /g or more. On the other hand, the BET specific surface area of the Si source is, for example, 200 m ² /g or less. The average particle size (D ₅₀ ) of the Si source is, for example, 0.5 μm or more and 10 μm or less.

A method for producing the Si source (porous Si) includes, for example, a method of producing an alloy of Mg and Si (Mg—Si alloy) and then removing Mg from the Mg—Si alloy. Mg—Si alloys are obtained, for example, by heating a mixture of Mg and Si. The ratio of Mg to Si (Mg/Si) is, for example, 1.0 or more, may be 1.5 or more, or may be 2.0 or more. On the other hand, Mg/Si is, for example, 6.0 or less. As a method for removing Mg from the Mg—Si alloy, for example, the Mg—Si alloy is heated in an inert gas atmosphere containing oxygen to change Mg in the Mg—Si alloy to MgO, and then acid A method of removing MgO with a solution is mentioned. Acid solutions include, for example, aqueous solutions containing hydrochloric acid (HCl) and hydrogen fluoride (HF).

Further, as a method for producing a Si source (porous Si), for example, a method of producing an alloy of Li and Si (Li—Si alloy) and then removing Li from the Li—Si alloy can be mentioned. A Li—Si alloy is obtained, for example, by mixing Li and Si. The ratio of Li to Si (Li/Si) is, for example, 1.0 or more, may be 2.0 or more, may be 3.0 or more, or may be 4.0 or more. On the other hand, Li/Si is, for example, 8.0 or less. A method of removing Li from a Li—Si alloy includes, for example, a method of reacting the Li—Si alloy with a Li extraction material. Examples of the Li extraction material include alcohols such as methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol and 1-hexanol; acids such as acetic acid, formic acid, propionic acid and oxalic acid.

In addition, as a method for producing a Si source (porous Si), for example, an alloy of Mg and Si (Mg—Si alloy) is produced, then Mg is removed from the Mg—Si alloy, and then Mg A method of manufacturing an alloy (Li—Si alloy) of Si and Li from which the is removed, and then removing Li from the Li—Si alloy.

On the other hand, the Na source contains at least Na. Na sources include, for example, metallic Na, NaH, and metallic Na dispersions in which particles of metallic Na are dispersed in oil.

Examples of the method of obtaining the Na—Si alloy by reacting the Na source and the Si source include a method of heating a mixture containing the Na source and the Si source. The heating temperature is, for example, 300° C. or higher, may be 310° C. or higher, may be 320° C. or higher, or may be 340° C. or higher. On the other hand, the heating temperature is, for example, 800° C. or lower, may be 600° C. or lower, or may be 450° C. or lower. Also, the alloying step is preferably performed in an inert atmosphere such as an Ar atmosphere.

The Na—Si alloy preferably has a Zintl phase. The Jintle phase has 2θ = 16.10°, 16.56°, 17.64°, 20.16°, 27.96°, 33.60°, 35.68 in X-ray diffraction measurement using CuKα rays. °, 40.22°, and 41.14°. These peak positions may vary within a range of ±0.50° or within a range of ±0.30°. The Na—Si alloy preferably has a zintol phase as a main phase. The Na—Si alloy may or may not have a silicon clathrate I type crystal phase.

The composition of the Na—Si alloy is not particularly limited, but is preferably represented by the composition of Na _z Si ₁₃₆ (121≦z≦151). z may be 126 or more, or 131 or more. On the other hand, z may be 141 or less. Elements other than Na and Si may be present in the Na—Si alloy. Other elements include, for example, Li, K, Rb, Cs, Ba, Ga, and Ge.

2. Silicon clathrate generation step The silicon clathrate generation step in the present disclosure is a step of heating the Na—Si alloy to reduce the amount of Na in the Na—Si alloy to generate a silicon clathrate II type crystal phase. be. In the silicon clathrate production step, a scavenger that scavenges Na in the Na—Si alloy is used.

An example of a scavenger is a Na getter agent that reacts with Na vapor generated from a Na—Si alloy. The Na getter agent is placed, for example, not in contact with the Na—Si alloy. Examples of Na getter agents include SiO, MoO ₃ and FeO. When using the Na getter agent, the silicon clathrate formation step is preferably performed in a reduced pressure atmosphere.

Other examples of scavengers include Na trapping agents that receive Na by reacting directly with Na—Si alloys. A Na trapping agent is placed in contact with, for example, a Na—Si alloy. Examples of Na trap agents include CaCl ₂ , AlF ₃ , CaBr ₂ , CaI ₂ , Fe ₃ O ₄ , FeO, MgCl ₂ , ZnO, ZnCl ₂ and MnCl ₂ . When using the Na trapping agent, the silicon clathrate formation step may be performed in a reduced pressure atmosphere or in a normal pressure atmosphere.

The heating temperature in the silicon clathrate forming step is, for example, 100° C. or higher, may be 200° C. or higher, or may be 270° C. or higher. On the other hand, the heating temperature is, for example, 500° C. or lower, and may be 400° C. or lower.

3. Active Material The active material obtained by each of the steps described above has a silicon clathrate II type crystal phase. In addition, the active material has voids inside the primary particles. With respect to the preferred range of the void volume of the active material, the preferred ranges of I _A /I _M and I _B /I _M , and other matters, the contents described in the above "A. Active material" can be referred to as appropriate. .

E. Negative electrode layer manufacturing method In the present disclosure, a negative electrode layer having an active material manufacturing step of manufacturing an active material by the above-described active material manufacturing method and a negative electrode layer forming step of forming a negative electrode layer using the active material. to provide a method of manufacturing

According to the present disclosure, by using the active material described above, it is possible to obtain a negative electrode layer whose volume change is small due to charging and discharging. The active material manufacturing process is the same as described in the above "D. Manufacturing method of active material". Moreover, the method for forming the negative electrode layer is not particularly limited, and a known method can be adopted. Examples of the method of forming the negative electrode layer include a method of applying slurry containing at least an active material to the negative electrode current collector and drying the slurry.

When forming the negative electrode layer, a press treatment for pressing the negative electrode layer in the thickness direction may be performed. Examples of press treatment include roller press and flat plate press. When the pressure of the pressing process is high, the voids in the negative electrode active material may be crushed. Through the press treatment, the void volume D of voids having a pore diameter of 50 nm or less in the active material may be 0.035 cc/g or more and 0.11 cc/g or less. Further, the void amount D may be set to 0.04 cc/g or more, 0.06 cc/g or more, or 0.08 cc/g or more by pressing. On the other hand, the void amount D may be reduced to 0.105 cc/g or less or 0.10 cc/g or less by press processing. Moreover, the ratio of the void amount D to the void amount C (D/C) is usually less than 1, and may be 0.7 or less. On the other hand, D/C is, for example, 0.3 or more, and may be 0.35 or more. It should be noted that D/C is approximately 1 when the pressure of the pressing process is not so high.

In addition, the above press treatment may set the void volume E of voids having a pore diameter of 100 nm or less in the active material to 0.053 cc/g or more and 0.16 cc/g or less. Further, the void amount E may be set to 0.09 cc/g or more and 0.14 cc/g or less by press processing.

In addition, with respect to the preferable aspect of the negative electrode layer to be obtained, the content described in the above "B. Negative electrode layer" can be cited as appropriate.

F. Battery manufacturing method In the present disclosure, manufacturing of a battery having an active material manufacturing step of manufacturing an active material by the above-described active material manufacturing method and a negative electrode layer forming step of forming a negative electrode layer using the active material provide a way.

According to the present disclosure, by using the active material described above, it is possible to obtain a battery whose volume change is small due to charging and discharging. The active material manufacturing process and the negative electrode layer forming process are the same as those described in the above "D. Manufacturing method of active material" and the above "E. Manufacturing method of negative electrode layer". Moreover, the method for forming the battery is not particularly limited, and a known method can be adopted. In addition to the active material manufacturing step and the negative electrode layer forming step, the method for manufacturing a battery according to the present disclosure includes a positive electrode layer forming step for forming a positive electrode layer, an electrolyte layer forming step for forming an electrolyte layer, a positive electrode layer, an electrolyte layer and a and an arrangement step of arranging the negative electrode layers in this order. With regard to preferred aspects of the obtained battery, the content described in the above "C. Battery" can be cited as appropriate.

Note that the present disclosure is not limited to the above embodiments. The above embodiment is an example, and any device that has substantially the same configuration as the technical idea described in the claims of the present disclosure and produces the same effect is the present invention. It is included in the technical scope of the disclosure.

[Example 1]
Si powder (Si powder having no voids inside primary particles, SIE23PB manufactured by Kojundo Chemical Co., Ltd.) was prepared as a Si source. Using this Si source and using NaH as the Na source, a Na—Si alloy was produced. As NaH, what was washed with hexane in advance was used. The Na source and the Si source were weighed so that the molar ratio was 1.05:1, and mixed using a cutter mill. This mixture was heated in a heating furnace in an Ar atmosphere at 400° C. for 40 hours to obtain a powdery Na—Si alloy.

Using the obtained Na—Si alloy and AlF ₃ as a Na trapping agent, a silicon clathrate formation step was carried out by a solid-phase method. A Na—Si alloy and AlF ₃ were weighed so as to have a molar ratio of 1:0.35 and mixed using a cutter mill to obtain a reaction raw material. The obtained powdery reaction raw material was placed in a stainless steel reaction vessel and heated in a heating furnace under an Ar atmosphere at 310° C. for 60 hours to cause a reaction. The resulting reaction product is believed to contain the desired active material and NaF and Al as by-products. The reaction product was washed with a mixed solvent of HNO ₃ and H ₂ O at a volume ratio of 90:10. By-products in the reaction product were thereby removed. After washing, it was filtered, and the filtered solid content was dried at 120° C. for 3 hours or more to obtain a powdery active material.

[Example 2]
Mg powder and Si powder were weighed so that the molar ratio would be 2.02:1, mixed in a mortar, and heated in a heating furnace under Ar atmosphere at 580° C. for 12 hours to obtain these. reacted. After cooling to room temperature, ingot-like Mg ₂ Si was obtained. Mg ₂ Si was pulverized at 300 rpm for 3 hours with a ball mill using zirconia balls with a diameter of 3 mm. After that, the pulverized Mg ₂ Si is heated at 580 ° C. for 12 hours in a heating furnace under the flow of a mixed gas in which Ar and O ₂ are mixed at a volume ratio of 95:5 to remove oxygen in the mixed gas. and Mg ₂ Si were reacted. The resulting reaction product is believed to contain Si and MgO. The reaction product was washed with a mixed solvent of H ₂ O, HCl and HF in a volume ratio of 47.5:47.5:5. This removed the oxide film on the Si surface and MgO in the reaction product. After washing, it was filtered, and the filtered solid content was dried at 120° C. for 3 hours or more to obtain powdery porous Si. An active material was obtained in the same manner as in Example 1, except that the obtained porous Si was used as the Si source instead of the Si powder.

[Example 3]
Metallic Li and Si powder were weighed so that the molar ratio was 4:1, and they were reacted by mixing them in a mortar under the conditions of room temperature and Ar atmosphere for 0.5 hours. Thus, Li ₄ Si was obtained. The resulting Li ₄ Si was reacted with ethanol under Ar atmosphere. The resulting reaction product is believed _to contain Si and _CH3CH2OLi . This reaction product was filtered, and the filtered solid content was dried at 120° C. for 3 hours or more to obtain powdery porous Si. An active material was obtained in the same manner as in Example 1, except that the obtained porous Si was used as the Si source instead of the Si powder.

[Comparative Example 1]
Using Si particles as the Si source and using Na particles as the Na source, the Si particles and Na particles are mixed so that the molar ratio is 1:1, put into a crucible, sealed under an Ar atmosphere, and heated at 700 ° C. After heating, a Na—Si alloy was obtained. The obtained Na—Si alloy was heated under vacuum (about 1 Pa) at 340° C. to remove Na, thereby obtaining an intermediate having a silicon clathrate II type crystal phase. The obtained intermediate and Li metal were weighed at a molar ratio of Li/Si=1.7 and mixed in a mortar in an Ar atmosphere to obtain an alloy compound. The obtained alloy compound was reacted with ethanol in an Ar atmosphere to form voids inside the primary particles and obtain an active material.

[evaluation]
(XRD measurement)
The active materials obtained in Examples 1 to 3 and Comparative Example 1 were subjected to X-ray diffraction (XRD) measurement using CuKα rays. As a result, as shown in FIG. 4, it was confirmed that all the active materials had a silicon clathrate II type crystal phase as a main phase.

The intensity of peak A located near 2θ=20.09° in the crystal phase of silicon clathrate type II was defined as _IA , and the intensity of peak B located near 2θ=31.72° was defined as _IB . . Further, I _M was the maximum intensity at 2θ=22° to 23°, and I _A /I _M and I _B /I _M were obtained. Table 1 shows the results.

(Measurement of void volume)
The void volume of the Si source (base material) used in Examples 1 to 3 and Comparative Example 1 was determined. Similarly, the void volumes of the active materials obtained in Examples 1 to 3 and Comparative Example 1 were determined. A mercury porosimeter was used to measure the void volume. A Pore Master 60-GT (Quanta Chrome Co.) was used as the measurement apparatus, and the measurement was carried out in the range of 40 Å to 4,000,000 Å. The Washburn method was used for the analysis. Table 1 shows the results.

As shown in Table 1, in Example 1, the void volume B was larger than in Comparative Example 1. Moreover, in Examples 2 and 3, the void amount A and the void amount B were larger than in Comparative Example 1. Moreover, in Examples 1 to 3 and Comparative Example 1, I _A /I _M and I _B /I _M were all greater than 1, and it was confirmed that a silicon clathrate II type crystal phase was formed. . Further, as shown in Examples 2 and 3, by clathrate-forming a base material having a large amount of voids C, an active material having large amounts of voids A and B was obtained.

In Comparative Example 1, Si was subjected to clathrate formation (Na alloying and Na desorption treatment), and then to porosity. In this case, if the amount of Li used for porosification is increased, the crystal phase of the silicon clathrate II type may disappear, so the amount of Li used is limited. On the other hand, in Examples 2 and 3, Si was made porous and then clathrated. In this case, the amount of Li used for porosification can be increased, and sufficient porosity can be obtained. On the other hand, when sufficiently porous Si is clathrated at high temperature, minute voids may disappear. In contrast, in Examples 2 and 3, clathrate formation is possible at low temperature by using a scavenger. As a result, it is presumed that the active materials obtained in Examples 2 and 3 had a large amount of voids A and B.

[Example 4]
Using the active material obtained in Example 1 as a negative electrode active material, an all solid state battery was produced.

(Preparation of negative electrode)
A polypropylene container contains the active material obtained in Example 1, a sulfide solid electrolyte (Li ₂ SP ₂ S ₅ -based glass ceramic), a conductive material (VGCF), and a PVDF-based binder at a rate of 5% by weight. A butyl butyrate solution and butyl butyrate were added and stirred for 30 seconds with an ultrasonic dispersion device (UH-50 manufactured by SMTE). Next, the container was shaken for 30 minutes with a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.). It was applied onto a negative electrode current collector (Cu foil, manufactured by UACJ) by a blade method using an applicator, and dried on a hot plate at 100° C. for 30 minutes. As a result, a negative electrode having a negative electrode current collector and a negative electrode layer was obtained.

(Preparation of positive electrode)
A positive electrode active material (LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , average particle diameter 6 μm), a sulfide solid electrolyte (Li ₂ SP ₂ S ₅ glass ceramic), and a conductive material were placed in a polypropylene container. (VGCF), a butyl butyrate solution containing a PVDF binder at a rate of 5% by weight, and butyl butyrate were added and stirred for 30 seconds with an ultrasonic dispersing device (UH-50 manufactured by SMTE). Next, the container was shaken for 3 minutes with a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.). An applicator was used to apply the solution onto a positive current collector (Al foil, manufactured by Showa Denko) by a blade method, followed by drying on a hot plate at 100° C. for 30 minutes. As a result, a positive electrode having a positive electrode current collector and a positive electrode layer was obtained. The area of the positive electrode was smaller than that of the negative electrode.

(Preparation of solid electrolyte layer)
A sulfide solid electrolyte (Li ₂ SP ₂ S ₅ glass ceramic), a heptane solution containing 5% by weight of a butylene rubber binder, and heptane are added to a polypropylene container, and an ultrasonic dispersion device ( The mixture was stirred for 30 seconds with UH-50 manufactured by SMTE. Next, the container was shaken for 30 minutes with a shaker (TTM-1, manufactured by Shibata Scientific Co., Ltd.). It was applied onto a release sheet (Al foil) by a blade method using an applicator and dried on a hot plate at 100°C for 30 minutes. As a result, a transfer member having a release sheet and a solid electrolyte layer was obtained.

(Fabrication of all-solid-state battery)
A solid electrolyte layer for bonding was placed on the positive electrode layer of the positive electrode, set in a roll press, and pressed at 100 kN/cm and 165°C. Thus, a first laminate was obtained.

Next, the negative electrode was set in a roll press and pressed at 60 kN/cm and 25°C. Thus, a pressed negative electrode was obtained. After that, a solid electrolyte layer for bonding and a transfer member were arranged in order from the negative electrode layer side. At this time, the bonding solid electrolyte layer and the solid electrolyte layer of the transfer member were arranged so as to face each other. The obtained laminate was set in a flat uniaxial press and temporarily pressed at 100 MPa and 25° C. for 10 seconds. After that, the release sheet was peeled off from the solid electrolyte layer. Thus, a second laminate was obtained.

Next, the solid electrolyte layer for bonding in the first laminate and the solid electrolyte layer in the second laminate are arranged so as to face each other, set in a flat uniaxial press, and press at 200 MPa and 120° C. for 1 minute. pressed. Thus, an all-solid battery was obtained.

[Example 5]
An all-solid battery was obtained in the same manner as in Example 4, except that the active material obtained in Example 2 was used as the negative electrode active material.

[Example 6]
An all-solid battery was obtained in the same manner as in Example 4, except that the active material obtained in Example 3 was used as the negative electrode active material.

[Comparative Example 2]
An all-solid battery was obtained in the same manner as in Example 4, except that the active material obtained in Comparative Example 1 was used as the negative electrode active material.

[evaluation]
(Measurement of void volume)
The amount of voids in the negative electrode active material of the pressed negative electrodes produced in Examples 4 to 6 and Comparative Example 2 was determined. The method for measuring the void volume is the same as described above. Table 2 shows the results.

(Measurement of increase in confining pressure)
The all-solid-state batteries obtained in Examples 4 to 6 and Comparative Example 2 were charged, and the increase in confining pressure was measured. The test conditions were a confining pressure (fixed dimension) of 5 MPa, a charge of 0.1 C, and a cut voltage of 4.55 V. The confining pressure at 4.55 V was measured to determine the amount of increase in the confining pressure from the state before charging. Table 2 shows the results. It should be noted that the results of the amount of increase in confining pressure in Table 2 are relative values when the result of Comparative Example 2 is set to 100.

As shown in Table 2, in Examples 4 to 6, compared with Comparative Example 2, it was confirmed that the amount of increase in confining pressure was smaller. It is presumed that this is because the negative electrode active materials obtained in Examples 4 to 6 have many minute voids with pore diameters of 50 nm or less even after being pressed.

[Example 7]
Powdery porous Si was obtained in the same manner as in Example 3. Except that the obtained porous Si was used as the Si source instead of the Si powder, and the heating conditions after the addition of _AlF3 were changed from 310 ° C., 60 hours to 310 ° C., 120 hours. An active material was obtained in the same manner as in Example 1.

[Example 8]
Powdery porous Si was obtained in the same manner as in Example 3. Except that the obtained porous Si was used as the Si source instead of the Si powder, and that the heating conditions after the addition of _AlF3 were changed from 310 ° C., 60 hours to 290 ° C., 120 hours. An active material was obtained in the same manner as in Example 1.

[Example 9]
Powdery porous Si was obtained in the same manner as in Example 3. An active material was obtained in the same manner as in Example 1, except that the obtained porous Si was used as the Si source instead of the Si powder. After that, the obtained active material was washed by being immersed in an aqueous HF solution for 3 hours (HF washing).

[Example 10]
Powdery porous Si (first porous Si) was obtained in the same manner as in Example 2. Powdered porous Si (second porous Si) was obtained in the same manner as in Example 3, except that the obtained first porous Si was used instead of the Si powder. An active material was obtained in the same manner as in Example 1, except that the obtained second porous Si was used as the Si source instead of the Si powder.

[Example 11]
A second porous Si was obtained in the same manner as in Example 10. Except that the obtained second porous Si was used as the Si source instead of the Si powder, and that the heating conditions after the addition of _AlF3 were changed from 310°C for 60 hours to 270°C for 120 hours. , an active material was obtained in the same manner as in Example 1.

[Example 12]
An active material was obtained in the same manner as in Example 10. After that, the obtained active material was washed by being immersed in an aqueous HF solution for 3 hours (HF washing).

[evaluation]
(XRD measurement)
The active materials obtained in Examples 7 to 12 were subjected to X-ray diffraction (XRD) measurement using CuKα rays. As a result, it was confirmed that all the active materials had a silicon clathrate II type crystal phase as a main phase.

The intensity of peak A located near 2θ=20.09° in the crystal phase of silicon clathrate type II was defined as _IA , and the intensity of peak B located near 2θ=31.72° was defined as _IB . . Further, I _M was the maximum intensity at 2θ=22° to 23°, and I _A /I _M and I _B /I _M were obtained. Table 3 shows the results.

(Measurement of void volume)
The void volume of the active materials obtained in Examples 7 to 12 was determined. The method for measuring the void volume is the same as described above. Table 3 shows the results. For Example 9, the amount of voids in the negative electrode active material in the pressed negative electrode was determined. As a result, the void volume D of voids with a pore diameter of 50 nm or less was 0.110 cc/g, and the void volume E of voids with a pore diameter of 100 nm or less was 0.156 cc/g.

(Measurement of increase in confining pressure)
All-solid-state batteries were obtained in the same manner as in Example 4 using the active materials obtained in Examples 7 to 12. The obtained all-solid-state battery was charged, and the increase in confining pressure was measured. The test conditions are the same as above. Table 3 shows the results. It should be noted that the results of the amount of increase in confining pressure in Table 3 are relative values when the result of Comparative Example 2 is set to 100.

As shown in Table 3, in Examples 7 to 12, compared with Comparative Example 2, it was confirmed that the amount of increase in confining pressure was smaller. It is presumed that this is because the active materials obtained in Examples 7 to 12 have many minute voids with pore diameters of 50 nm or less even after being pressed.

DESCRIPTION OF SYMBOLS 1... Positive electrode layer 2... Negative electrode layer 3... Electrolyte layer 4... Positive electrode collector 5... Negative electrode collector 10... Battery

Claims (11)

Having a silicon clathrate type II crystal phase,
Having voids inside the primary particles,
The active material, wherein the void volume A of the voids having a pore diameter of 100 nm or less is greater than 0.15 cc/g and equal to or less than 0.40 cc/g. Having a silicon clathrate type II crystal phase,
Having voids inside the primary particles,
The active material, wherein the void volume B of the voids having a pore diameter of 50 nm or less is greater than 0.065 cc/g and equal to or less than 0.25 cc/g. 3. The active material according to claim 2, wherein the void volume A of the voids having a pore diameter of 100 nm or less is 0.05 cc/g or more and 0.40 cc/g or less. In the X-ray diffraction measurement using CuKα rays, peak A located at 2θ = 20.09° ± 0.50° and 2θ = 31.72° ± A peak B located at 0.50° is observed,
I _A /I _M is 1.75 or more, where I A is the intensity of the peak A _, I _B is the intensity of the peak B, and I _M is the maximum intensity at 2θ=22° to 23°2. 00 or less, and I _B /I _M is 1.35 or more and 1.75 or less. A negative electrode layer containing the active material according to claim 1 . A battery comprising a positive electrode layer, a negative electrode layer, and an electrolyte layer disposed between the positive electrode layer and the negative electrode layer,
A battery, wherein the negative electrode layer is the negative electrode layer according to claim 5 . A method for producing the active material according to claim 1 or 2,
an alloying step of reacting a Na source and a Si source to obtain a Na—Si alloy;
a silicon clathrate forming step of heating the Na—Si alloy to reduce the amount of Na in the Na—Si alloy to form a silicon clathrate II type crystal phase;
In the silicon clathrate generation step, using a scavenger that captures Na in the Na—Si alloy,
A method for producing an active material, wherein particles having pores with a pore diameter of 50 nm or less and a void volume C of 0.02 cc/g or more and 0.20 cc/g or less are used as the Si source. an active material manufacturing process for manufacturing an active material by the method for manufacturing an active material according to claim 7;
a negative electrode layer forming step of forming a negative electrode layer using the active material;
A method for producing a negative electrode layer having The negative electrode layer forming step includes a pressing process for pressing the negative electrode layer in a thickness direction,
9. The negative electrode layer according to claim 8, wherein the press treatment sets the void volume D of the voids having a pore diameter of 50 nm or less in the active material to 0.035 cc/g or more and 0.11 cc/g or less. manufacturing method. 10. The negative electrode layer according to claim 9, wherein the press treatment reduces the void volume E of the voids having a pore diameter of 100 nm or less in the active material to 0.053 cc/g or more and 0.16 cc/g or less. manufacturing method. an active material manufacturing process for manufacturing an active material by the method for manufacturing an active material according to claim 7;
a negative electrode layer forming step of forming a negative electrode layer using the active material;
A method for manufacturing a battery having

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