CN117083734A - Negative electrode material, battery, method for producing negative electrode material, and method for producing battery - Google Patents

Negative electrode material, battery, method for producing negative electrode material, and method for producing battery Download PDF

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Publication number
CN117083734A
CN117083734A CN202280025583.6A CN202280025583A CN117083734A CN 117083734 A CN117083734 A CN 117083734A CN 202280025583 A CN202280025583 A CN 202280025583A CN 117083734 A CN117083734 A CN 117083734A
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China
Prior art keywords
silicon
negative electrode
particles
electrode material
carbon
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Chinese (zh)
Inventor
中田嘉信
力田直树
唐捷
张坤
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Mitsubishi Materials Corp
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Mitsubishi Materials Corp
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Priority claimed from JP2021168448A external-priority patent/JP2022161801A/en
Application filed by Mitsubishi Materials Corp filed Critical Mitsubishi Materials Corp
Priority claimed from PCT/JP2022/012756 external-priority patent/WO2022215498A1/en
Publication of CN117083734A publication Critical patent/CN117083734A/en
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Abstract

Improving the performance. The negative electrode material is a negative electrode material of a battery, comprising: carbon, tungsten trioxide and silicon particles (33) containing silicon, wherein when the silicon particles (33) are measured by X-ray photoelectron spectroscopy, the Si content of Si2p from elemental silicon and the SiO from the surface layer 2 The Si content ratio of Si2p is 3 or more based on the atomic concentration.

Description

Negative electrode material, battery, method for producing negative electrode material, and method for producing battery
Technical Field
The present invention relates to a negative electrode material, a battery, a method for producing a negative electrode material, and a method for producing a battery.
Background
As a negative electrode material of the lithium ion secondary battery, carbon is sometimes used. For example, patent document 1 describes a negative electrode in which tungsten trioxide is disposed on the surface of graphite. By disposing tungsten trioxide on the surface of graphite, the diffusivity of lithium ions can be improved, and the performance of the battery can be improved. For example, patent document 2 describes a negative electrode including silicon particles (silicon), tungsten, and carbon.
Patent document 1: japanese patent application laid-open No. 2018-45904
Patent document 2: japanese patent application laid-open No. 2015-125816
Performance can be improved by disposing tungsten trioxide and silicon in the anode material, but there is room for improvement in performance improvement.
Disclosure of Invention
The present invention has been made in view of the above circumstances, and an object thereof is to provide a negative electrode material, a battery, a method for producing the negative electrode material, and a method for producing the battery, each of which has improved performance.
In order to achieve the above object, a negative electrode material according to the present disclosure is a negative electrode material for a battery, comprising: carbon, tungsten trioxide and silicon-containing silicon material, wherein when the silicon material is measured by X-ray photoelectron spectroscopy, the Si content of Si2p from elemental silicon and the SiO from the surface layer 2 The Si content ratio of Si2p is 3 or more based on the atomic concentration.
In order to achieve the above object, a battery according to the present disclosure includes: the negative electrode material; and a positive electrode material.
In order to solve the above problems, a method for producing a negative electrode material according to the present disclosure is a negative electrode of a batteryA method of manufacturing a polar material comprising: a step of preparing a silicon raw material in an atmosphere having an oxygen concentration of 5% or less; and a step of generating a negative electrode material containing carbon, tungsten trioxide and a silicon material using the silicon raw material; in the case of measuring the silicon material by X-ray photoelectron spectroscopy, the Si amount of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p is 3 or more based on the atomic concentration.
In order to achieve the above object, a method for manufacturing a battery according to the present disclosure includes: a method for producing the negative electrode material; and a step of manufacturing a positive electrode material.
According to the present invention, the performance of the anode material can be improved.
Drawings
Fig. 1 is a schematic partial cross-sectional view of a battery according to the present embodiment.
Fig. 2 is a schematic cross-sectional view of an example of the negative electrode according to the present embodiment.
Fig. 3 is a schematic cross-sectional view of a silicon material.
Fig. 4 is a diagram showing an example of a full spectrum of a silicon material according to XPS measurement results.
Fig. 5 is a diagram showing an example of a narrow spectrum of Si2p of a silicon material according to the measurement result of XPS.
Fig. 6 is a diagram showing an example of peak separation of Si2p in a silicon material according to XPS measurement results.
Fig. 7 is a diagram showing an example of a narrow spectrum of O1s of a silicon material according to the measurement result of XPS.
Fig. 8 is a flowchart illustrating steps for preparing a silicon feedstock.
Fig. 9 is a flowchart illustrating an example of a method for manufacturing a battery according to the present embodiment.
Fig. 10 is a flowchart illustrating an example of a method for manufacturing a battery according to the present embodiment.
FIG. 11 is a table showing production conditions, characteristics of silicon particles, and evaluation results of each example.
Detailed Description
The present invention will be described in detail below with reference to the drawings. The present invention is not limited to the following specific embodiments (hereinafter, referred to as embodiments). The constituent elements of the following embodiments include constituent elements that can be easily assumed by those skilled in the art, substantially identical constituent elements, and constituent elements within a so-called equivalent range. The constituent elements disclosed in the following embodiments may be appropriately combined.
(Battery)
Fig. 1 is a schematic partial cross-sectional view of a battery according to the present embodiment. The battery 1 according to the present embodiment is a lithium ion secondary battery. The battery 1 includes a case 10, an electrode group 12, and an electrolyte, not shown. The case 10 is a case that accommodates the electrode group 12 and the electrolyte therein. In addition to the electrode group 12, the case 10 may be provided with wiring, terminals, and the like connected to the electrode group 12.
The electrode group 12 includes a negative electrode 14, a positive electrode 16, and a separator 18. The electrode group 12 is configured such that a separator 18 is disposed between the negative electrode 14 and the positive electrode 16. In the example of fig. 1, the electrode group 12 is a so-called stacked electrode group structure in which rectangular negative electrodes 14 and rectangular positive electrodes 16 are alternately stacked with a rectangular separator 18 interposed therebetween. However, the electrode group 12 is not limited to the stacked electrode group structure. For example, the electrode assembly 12 may be a wound electrode assembly in which the strip-shaped negative electrode 14 and the strip-shaped positive electrode 16 are stacked with the strip-shaped separator 18 interposed therebetween and wound.
(negative electrode)
Fig. 2 is a schematic cross-sectional view of an example of the negative electrode according to the present embodiment. As shown in fig. 2, the negative electrode 14 includes a current collecting layer 20 and a negative electrode material layer 22. The current collecting layer 20 is a layer made of a conductive member. Examples of the conductive member of the current collecting layer 20 include copper. The anode material layer 22 is a layer containing the anode material according to the present embodiment. The negative electrode material layer 22 is provided on the surface of the current collector layer 20. The thickness of the current collecting layer 20 may be, for example, 15 μm or more and 40 μm or less, and the thickness of the negative electrode material layer 22 may be, for example, 20 μm or more and 200 μm or less. The negative electrode 14 may include a negative electrode material layer 22 on both sides of the current collector layer 20.
The anode material layer 22 contains an anode material. The negative electrode material contains carbon, tungsten trioxide and a silicon material. The negative electrode material of the present embodiment has tungsten trioxide on the carbon surface and a silicon material on the carbon surface, but the positional relationship of carbon, tungsten trioxide, and silicon material is not limited to these, and may be any positional relationship. More specifically, the anode material of the anode material layer 22 contains carbon particles 30, which are particles of carbon, and tungsten trioxide particles WO 3 The (tungsten trioxide) particles 32 and silicon particles 33 which are particles containing silicon. The shape of the particles herein is not limited to a sphere, and may be any shape such as a linear shape or a flake shape.
The tungsten trioxide provided on the carbon surface comprises: at least one of the case where tungsten trioxide is directly fixed to carbon, the case where tungsten trioxide is indirectly fixed to carbon via silicon fixed to carbon, the case where silicon is indirectly fixed to carbon via tungsten trioxide fixed to carbon, and the case where composite particles of tungsten trioxide and silicon are directly fixed to carbon are directly or indirectly fixed to carbon. The negative electrode material of the present embodiment preferably contains at least carbon and a silicon material to which tungsten trioxide is fixed. The negative electrode material of the present embodiment may be made of carbon, tungsten trioxide, or a silicon material, or may be free of carbon, tungsten trioxide, or a material other than a silicon material, except for unavoidable impurities. The negative electrode material of the present embodiment may contain unavoidable impurities in the remaining portion.
The anode material of the anode material layer 22 contains a plurality of carbon particles 30. The carbon particles 30 comprise amorphous carbon or graphite.
Amorphous carbon is amorphous carbon that does not have a crystal structure. Amorphous carbon is sometimes referred to as amorphous carbon or diamond-like carbon, and can be said to be carbon in which sp2 bonds and sp3 bonds are mixed. The carbon particles of amorphous carbon are composed entirely of amorphous carbon, and preferably contain no component other than amorphous carbon, except unavoidable impurities. Specifically, the carbon particles of amorphous carbon preferably do not contain graphite.
In addition, the amorphous carbon may contain a functional group (for example, a hydroxyl group or a carboxyl group) on the surface when the surface is treated with tungsten trioxide. Therefore, by the functional group, tungsten trioxide can be appropriately trapped on the surface of amorphous carbon, and tungsten trioxide can be appropriately disposed on the surface. Further, since tungsten trioxide is fixed to the surface of amorphous carbon by the functional group, adhesion of tungsten trioxide to the surface of amorphous carbon can be increased, and separation of tungsten trioxide from the carbon surface can be suppressed. In particular, since the hard carbon material is produced at a lower temperature than graphite, for example, the functional groups are easily retained and not removed, and tungsten trioxide and silicon can be appropriately disposed on the surface.
Graphite is carbon with a planar crystal structure.
The average particle diameter of the carbon particles 30 is preferably 1 μm or more and 50 μm or less, more preferably 1 μm or more and 20 μm or less. When the average particle diameter is within this range, the strength of the electrode film can be maintained.
The anode material of the anode material layer 22 further includes a plurality of WO 3 A particle 32 and a plurality of silicon particles (silicon material) 33. In more detail, a plurality of WO are provided for each carbon particle 30 3 Particles 32 and a plurality of silicon particles 33. Multiple WO' s 3 WO for one of the particles 32 3 The particles 32 are disposed on the surface of the carbon particles 30. And, a plurality of WO 3 WO for the other of particles 32 3 The particles 32 are provided on the surface of the silicon particles 33. More specifically, the silicon particles 33 are closely adhered (contacted) to the surfaces of the carbon particles 30, and the surfaces of the silicon particles 33 are closely adhered (contacted) to WO 3 Particles 32. Carbon particles 30, WO 3 The particles 32 and the silicon particles 33 may be combined. Further, carbon particles 30 and silicon particles 33 may be combined, and carbon particles 30 and WO may be combined 3 The particles 32 are composited. Thus, the anode material of the anode material layer 22 is carbon particles 30, WO 3 The structure in which the particles 32 and the silicon particles 33 are combined may further include a structure in which the carbon particles 30 and the silicon particles 33 are combined, and the carbon particles 30 and WO 3 At least any one of the structures in which the particles 32 are composited.
The compounding means that the silicon particles 33 cannot be pulled apart from the carbon particles 30 and the silicon particles 33 cannot be pulled from WO at least when no external force is applied 3 The particles 32 pull apart and cannot pull WO 3 The particles 32 are pulled away from the carbon particles 30. For example, the external force is a force when an SEI (Solid Electrolyte Interphase, solid electrolyte interface) film is formed to cover the entire surface layer and is expanded and contracted during operation of a battery using a negative electrode material.
For example, the compounding includes: silicon particles 33 are arranged on the surfaces of the carbon particles 30, and WO is arranged on the surfaces of the silicon particles 33 3 In the case of the composite of particles 32, WO is disposed on the surface of carbon particles 30 3 Particles 32 and in WO 3 In the case of a composite in which silicon particles 33 are arranged on the surface of particles 32, in the case of a composite in which silicon particles 33 are arranged on the surface of carbon particles 30, in the case of a composite in which WO is arranged on the surface of carbon particles 30 3 In the case of the composite of particles 32, WO is disposed on the surface of the silicon particles 33 3 In the case of the composite of particles 32, WO is disposed on the surface of carbon particles 30 3 Particle 32 and silicon particle 33 and WO 3 At least any one of the particles 32 and the silicon particles 33 is in close contact with each other.
WO 3 Particles 32 comprise WO of hexagonal crystal structure 3 WO for particles and monoclinic, triclinic, orthorhombic crystal structures 3 And (3) particles. That is, the anode material contains tungsten trioxide of hexagonal crystal structure and tungsten trioxide of monoclinic and triclinic crystal structures. However, the anode material may contain at least one of tungsten trioxide of hexagonal crystal structure, tungsten trioxide of monoclinic crystal structure, and tungsten trioxide of triclinic crystal structure. In summary, the negative electrode material preferably contains tungsten trioxide of at least one of hexagonal, monoclinic, and triclinic, more preferably contains tungsten trioxide of hexagonal and monoclinic or triclinic, and still more preferably contains tungsten trioxide of hexagonal, monoclinic, and triclinic. In the case where the negative electrode material contains tungsten trioxide having a different crystal structure such as monoclinic or triclinic in addition to hexagonal tungsten trioxide, it is preferable that the content of hexagonal tungsten trioxide be the largest among tungsten trioxide having each crystal structure. However, the crystal structure of tungsten trioxide contained in the negative electrode material is not limited to this, and may contain other crystal junctions, for example Structured tungsten trioxide. The negative electrode material may contain amorphous tungsten trioxide.
WO 3 The average particle diameter of the particles 32 is smaller than the average particle diameter of the carbon particles 30. WO (WO) 3 The average particle diameter of the particles 32 is preferably 100nm or more and 20 μm or less, more preferably 100nm or more and 1 μm or less.
As described above, the negative electrode material is a material in which tungsten trioxide in a particle form is provided on the surface of the carbon particles 30 (WO 3 Particles 32) and silicon (silicon particles 33), but is not limited thereto. The negative electrode material may be any material as long as it has a structure in which tungsten trioxide and a silicon material are provided on the surface of carbon, and the shape of the tungsten trioxide and the silicon material provided on the surface of carbon may be any shape. In this embodiment, tungsten trioxide is used as a tungsten compound or tungsten oxide. In the present embodiment, silicon is used as the silicon particles 33, but a silicon compound may be used.
The negative electrode material layer 22 may contain a negative electrode material (carbon particles 30, WO) 3 Particles 32 and silicon particles 33). The anode material layer 22 may contain a binder, for example. The binder may be any material, and examples thereof include polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), styrene Butadiene Rubber (SBR), and polyacrylic acid (PAA). The binder may be used alone or in combination of two or more. However, in the case where the carbon particles 30 are amorphous carbon, the anode material layer 22, in other words, the anode material preferably does not contain graphite.
The identification of carbon, tungsten trioxide and silicon can be performed by X-ray diffraction. For example, a peak waveform in an X-ray diffraction analysis result of an analyte shows a peak waveform of carbon, but when the (002) peak waveform in a known graphite structure is widened, it can be determined as amorphous carbon. For example, when the position (angle) of the display peak in the X-ray diffraction analysis result of the analysis target matches the position of the display peak in the known tungsten trioxide, it can be determined that the analysis target contains tungsten trioxide. For example, when the position (angle) of the display peak in the X-ray diffraction analysis result of the analysis target matches the known position of the display peak in silicon, it can be determined that the analysis target contains silicon.
And, WO 3 The arrangement of the particles 32 and the silicon particles 33 on the surface of the carbon particles 30 can be confirmed by observation with an electron microscope such as SEM (Scanning Electron Microscope ) or TEM (Transmission Electron Microscope, transmission electron microscope).
The element ratios of carbon, tungsten trioxide, and silicon in the anode material of the present embodiment can be measured by a luminescence analysis method.
The chemical components of silicon, tungsten, and oxygen are measured for the anode material of the present embodiment, and the balance may be carbon. Silicon and tungsten can be measured by ICP-OES (Inductivity Coupled Plasma Optical Emission Spectrometer, inductively coupled plasma atomic emission spectrometry) (manufacturer "Agilent", device product name "720-ES"), and oxygen can be measured by inert gas melting-infrared absorption (manufacturer "LECO", device product name "ONH 836"). In the negative electrode material as a product, when the total of three elements, i.e., the silicon material, tungsten trioxide, and carbon is 100 wt%, the content of the silicon material is preferably 1 wt% or more and 10 wt% or less, more preferably 1 wt% or more and 8 wt% or less, or 2 wt% or more and 8 wt% or less, and still more preferably 1.5 wt% or more and 7 wt% or 1.8 wt% or more and 7 wt% or less. In the negative electrode material as a product, when the total of three elements, i.e., the silicon material, tungsten trioxide, and carbon is 100 wt%, the content of tungsten trioxide is preferably 1 wt% or more and 10 wt% or less, more preferably 2 wt% or more and 8 wt% or less, and still more preferably 3 wt% or more and 5 wt% or less.
In the negative electrode material as a product, when the total of three elements, i.e., a silicon material, tungsten trioxide, and carbon is 100 wt%, the ratio of the content (wt%) of the silicon material to the content (wt%) of tungsten trioxide is preferably 0.2 or more and 2.5 or less, more preferably 0.2 or more and 2.0 or less, or 0.5 or more and 2.0 or less, and still more preferably 0.3 or more and 1.8 or more and 1.7 or less.
In the negative electrode material of the negative electrode material layer 22, the silicon particles 3 may be 3-tightly (contact) with the surfaces of the carbon particles 30, while WO 3 The particles 32 may be in close contact with the surface of the carbon particles 30. In this case, the carbon particles 30 and the silicon particles 33 may be compounded, and the carbon particles 30 and WO 3 Particles 32 may be composited.
As described above, the negative electrode material is a material in which tungsten trioxide in a particle form is provided on the surface of the carbon particles 30 (WO 3 Particles 32) and silicon particles 33, but is not limited thereto. The negative electrode material may be any material as long as it has a structure in which tungsten trioxide and a silicon material are provided on the surface of carbon, and the shape of the tungsten trioxide and the silicon material provided on the surface of carbon may be any shape.
(silicon particles)
Fig. 3 is a schematic cross-sectional view of a silicon particle. As shown in fig. 3, the silicon particles 33 include a Si layer 33A and an oxide layer 33B. The Si layer 33A is a layer made of Si, and can be said to be a portion that becomes a core of the silicon particle 33. The Si layer 33A preferably contains no element other than Si except for unavoidable impurities. The oxide layer 33B is a layer formed on the surface of the Si layer 33A, and preferably covers the entire surface area of the Si layer 33A. The oxide layer 33B is said to be a layer that becomes the outermost surface of the silicon particles 33. The oxide layer 33B is made of silicon oxide (SiO x ) And (3) forming layers. Oxide layer 33B contains SiO 2 As silicon oxide, but may also contain SiO 2 Other silicon oxides may include, for example, siO. The oxide layer 33B preferably contains no element other than the element constituting the silicon oxide, except for unavoidable impurities.
(characteristics of silicon particles according to XPS)
Next, characteristics of the silicon particles 33 when measured by X-ray photoelectron spectroscopy (XPS: X-ray Photoelectron Spectroscopy) are described. Hereinafter, unless otherwise indicated, measurement conditions by X-ray photoelectron spectroscopy are as follows.
Measurement device: PHI5000 Versa Probe II (ULVAC-PHI, INCORPORATED. manufacturing)
Exciting X-rays: monochromatic AlK alpha line
Output power: 50W
Enable: 187.85eV (Supery), 46.95eV (Narrow)
Measurement interval: 0.8eV/step (Supervey), 0.1eV/step (Narrow)
Angle of extraction of photoelectrons from sample surface: 45 degree
X-ray diameter: 200 μm
(amount of Si from elemental silicon and Si from SiO) 2 Ratio of Si amount of (C)
In the case of measuring the silicon particles 33 by X-ray photoelectron spectroscopy, the Si amount of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p is 3.0 or more, preferably 3.5 or more, more preferably 4 or more, based on the atomic concentration.
The surface layer here refers to a range from the surface to a depth where photoelectrons can escape from the sample, and is described in, for example, paper j.d.lee et al Journal surface analysis Vol16, no.1 (2009) pp.42 to 63, fig. 5. In the case where the silicon particles 33 are measured by X-ray photoelectron spectroscopy under the above measurement conditions, the depth range in which photoelectrons can be observed may be referred to as a surface layer.
Since the extraction angle of the photoelectrons to the sample surface is 45 °, in the case of a plane such as a Si wafer, the measurement depth d=dcos θ of the detected photoelectrons (θ is the extraction angle of the photoelectrons to the sample surface, d is the escape depth of the photoelectrons) is 0.71 times that of θ=90°. However, since the measurement was performed by applying the granular silicon on a flat plate, it is considered that the photoelectrons mainly come from the surface of each particle facing the detector, and thus the extraction angle of the photoelectrons to the sample surface was not corrected.
Si of Si2p refers to Si atoms that emit electrons of 2p orbitals by X-ray photoelectron spectroscopy. From SiO 2 Si of Si2p of (2) refers to SiO which is a composition for emitting electrons of 2p orbitals by X-ray photoelectron spectroscopy 2 Si of Si2p from elemental silicon refers to Si constituting elemental silicon (metallic silicon) from which electrons of 2p orbitals are emitted by X-ray photoelectron spectroscopy.
Si amount of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p in (2) refers to the atomic concentration of Si (Si atoms) from elemental silicon that emits electrons of 2p orbitals and the atomic concentration of Si (Si atoms) from elemental silicon that emits electrons of 2p orbitals from the surface layer (here, for example, from the outermost surface of the silicon particle 33 to a position about 6 angstroms deeper than the outermost surface) 2 Atomic concentration ratio of Si (Si atoms). Si amount of Si2p from elemental silicon and SiO from silicon particles 33 2 The ratio of the Si2p content in the above range (3.0 or more based on the atomic concentration) reduces the oxide content in the vicinity of the surface, and can improve the capacity of the negative electrode material. Further, since the oxide layer on the surface becomes thin, li ions are easily intruded and released, and the resistance is lowered. Further, in the case of measuring the silicon particles 33 by X-ray photoelectron spectroscopy, the Si content of Si2p derived from elemental silicon and SiO derived from the surface layer 2 The Si content ratio of Si2p is preferably 9 or less, more preferably 19 or less, and even more preferably 99 or less based on the atomic concentration. Si amount and SiO by the Si particles 33 2 When the ratio of the amount of (b) is within this range (99 or less), it is not necessary to excessively prepare equipment or a process for preventing oxidation of silicon particles, the capacity of the anode material can be increased, and the decrease in productivity can be suppressed. In this way, when the silicon particles 33 are measured by X-ray photoelectron spectroscopy, the Si content of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p is preferably 3 to 9, more preferably 3 to 19, still more preferably 3 to 99, based on the atomic concentration. Further, in the case of measuring the silicon particles 33 by X-ray photoelectron spectroscopy, the Si content of Si2p derived from elemental silicon and SiO derived from the surface layer 2 The Si content ratio of Si2p is preferably 3.5 to 9, more preferably 3.5 to 19, still more preferably 3.5 to 99, based on the atomic concentration. Further, in the case of measuring the silicon particles 33 by X-ray photoelectron spectroscopy, the Si content of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p is preferably 4 to 9, more preferably 4 to 19, still more preferably 4 to 99, based on the atomic concentration.
In additionFor example when from SiO 2 When the Si content of Si2p is 1%, si from Si2p of elemental silicon becomes 99%, so if the ratio is taken, si content of Si2p of elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p was 99. Likewise, when from SiO 2 When the Si content of Si2p is 5%, si from Si2p of elemental silicon becomes 95%, so if the ratio is taken, si content of Si2p of elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p was 19.
Here, siO from the measurement by X-ray photoelectron spectroscopy will be described 2 A method for calculating the ratio of Si amount of Si2p to Si amount of Si2p derived from elemental silicon. Fig. 4 is a diagram showing an example of a full spectrum of a silicon material according to the measurement result of XPS, fig. 5 is a diagram showing an example of a narrow spectrum of Si2p of a silicon material according to the measurement result of XPS, fig. 6 is a diagram showing an example of peak separation of a narrow spectrum of Si2p of a silicon material according to the measurement result of XPS, and fig. 7 is a diagram showing an example of a narrow spectrum of O1s of a silicon material according to the measurement result of XPS. Fig. 4 shows an example of the peak waveform P of the silicon particles 33 analyzed by the wide scan, and the peak waveform P1 around the binding energy 100eV shows the peak of Si 2P. Fig. 5 shows an example of a waveform of the silicon particles 33 analyzed by narrow scanning in the vicinity of the peak waveform P1, and the peaks of Si2P are extracted with the background removed. Here, from SiO 2 Si of Si2p and Si of Si2p derived from elemental silicon are different in bonding state and bonding energy. Therefore, as shown in FIG. 6, the peak waveform P1 can be separated into a peak waveform P1A showing Si2P from elemental silicon and a peak waveform P1A showing Si from SiO 2 Peak waveform P1B of Si2P of (B). The peak waveform P1A is a waveform having one peak around the binding energy 99eV, and the peak waveform P1B is a waveform having one peak around the binding energy 103 eV. Regarding background removal from the peak waveform, baseline correction was performed mainly in Shirley's method using Multipak version9.9.0.8 software attached to the X-ray photoelectron spectroscopy device.
In the present embodiment, the ratio of the area of the peak waveform P1A to the area of the peak waveform P1B is calculated as the Si amount of Si2P from elemental silicon and the Si amount from SiO based on the atomic concentration reference 2 Si2p of Si (Si 2 p).
(Si concentration ratio from Si)
The ratio of the atomic concentration of Si from Si2p of elemental silicon to the atomic concentration of Si of all Si2p (all Si from which electrons of 2p orbitals are emitted) in the surface layer of the silicon particle 33 is defined as the Si concentration ratio (first Si concentration) of Si. The Si concentration ratio from Si can be calculated as the ratio of the area of the peak waveform P1A to the area of the peak waveform P1. The Si concentration ratio from Si is preferably 75% or more, more preferably 77% or more, and even more preferably 80% or more. When the Si concentration ratio from Si falls within this range, the amount of oxide near the surface is reduced, and the capacity of the negative electrode material can be improved. The Si concentration ratio derived from Si is preferably 90% or less, more preferably 95% or less, and even more preferably 99% or less. By having the Si concentration ratio from Si within this range, it is not necessary to excessively prepare equipment or a process for preventing oxidation of silicon particles, the capacity of the anode material can be improved, and the reduction in productivity can be suppressed.
(from SiO) 2 Si concentration ratio of (2)
And, the surface layer of the silicon particle 33 is derived from SiO 2 The ratio of the atomic concentration of Si2p to the atomic concentration of Si of all Si2p is defined as SiO 2 Si concentration ratio of (2). From SiO 2 The Si concentration ratio of (c) can be calculated as the ratio of the area of the peak waveform P1B to the area of the peak waveform P1. From SiO 2 The Si concentration ratio of (2) is preferably 25% or less, more preferably 23% or less, and even more preferably 20% or less. By from SiO 2 When the Si concentration ratio is within this range, the amount of oxide near the surface is reduced, and the capacity of the negative electrode material can be improved. And from SiO 2 The Si concentration ratio of (2) is preferably 10% or more, more preferably 5% or more, and still more preferably 1% or more. By from SiO 2 In this range, it is not necessary to prepare excessively equipment or a process for preventing oxidation of silicon particles, the capacity of the anode material can be increased, and the reduction in productivity can be suppressed.
(ratio of Si amount to O amount)
When the silicon particles 33 are measured by X-ray photoelectron spectroscopy, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer is preferably 1.2 or more, more preferably 1.3 or more, and even more preferably 1.4 or more, based on the atomic concentration.
O1s refers to O atoms that emit electrons in the 1s orbit by X-ray photoelectron spectroscopy.
The ratio of the Si amount of Si2p to the O amount of O1s in the surface layer refers to the ratio of the atomic concentration of Si (Si atom emitting electrons of 2p orbitals) of Si2p in the surface layer of the silicon particle 33 (for example, from the outermost surface to a position about 6 angstroms deeper than the outermost surface) to the atomic concentration of O (O atom emitting electrons of 1s orbitals) of O1s in the surface layer of the silicon particle 33 (for example, from the outermost surface to a position about 10 angstroms deeper than the outermost surface). When the ratio of the Si amount of Si2p to the O amount of O1s in the silicon particles 33 falls within this range, the amount of oxide near the surface is reduced, and the capacity of the negative electrode material can be improved. In particular SiO 2 In such a case, the ratio of Si amount to O amount is within the above range, so that SiO may function as a factor for suppressing the increase in capacity 2 The amount of silicon oxide other than silicon oxide is reduced, and the capacity can be appropriately increased. When the silicon particles 33 are measured by X-ray photoelectron spectroscopy, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer is preferably 4 or less, more preferably 9 or less, and even more preferably 99 or less, based on the atomic concentration. When the ratio of the Si amount to the O amount of the silicon particles 33 is within this range, it is not necessary to prepare excessively pure Si, and the capacity of the anode material can be increased while suppressing a decrease in productivity. In this way, when the silicon particles 33 are measured by X-ray photoelectron spectroscopy, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer is preferably 1.2 or more and 4 or less, more preferably 1.2 or more and 9 or less, and still more preferably 1.2 or more and 99 or less, on an atomic concentration basis. When the silicon particles 33 are measured by X-ray photoelectron spectroscopy, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer is preferably 1.3 or more and 4 or less, more preferably 1.3 or more and 9 or less, and still more preferably 1.3 or more and 99 or less, on an atomic concentration basis. Further, in the case of measuring the silicon particles 33 by X-ray photoelectron spectroscopy The ratio of the Si content of Si2p to the O content of O1s in the surface layer is preferably 1.4 or more and 4 or less, more preferably 1.4 or more and 9 or less, and still more preferably 1.4 or more and 99 or less, based on the atomic concentration.
For example, when the O concentration is 20at% and the Si concentration is 80%, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer becomes 4, and when the O concentration is 5at% and the Si concentration is 95%, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer becomes 19.
Here, a method for calculating the ratio of the Si amount of Si2p to the O amount of O1s when measured by X-ray photoelectron spectroscopy will be described. Qualitative analysis called full spectrum of fig. 4 was performed. Next, for the element whose presence has been confirmed in the measurement of the full spectrum, a narrow spectrum corresponding to the binding energy of the orbital level specific to each element is measured. For example, fig. 5 shows a narrow spectrum of Si2P, and fig. 7 shows a narrow spectrum of O1 s. In addition, if trace elements are present, a narrow spectrum of the element is also measured. The background correction of each narrow spectrum was performed to determine the peak area. The peak area is multiplied by a sensitivity coefficient corresponding to the orbital energy level of each element as the concentration (atomic concentration) of the element. The series of atomic concentration calculations can be determined using the analytical software MultiPack attached to PHI5000 Versa ProbeII. The result of this determination is the Si concentration (second Si concentration) and the O concentration in fig. 11. From this concentration, the Si/O ratio was obtained.
That is, the ratio of the Si concentration to the O concentration obtained as described above is the concentration ratio Si/O.
(Si concentration)
The Si concentration is preferably 50at% or more, more preferably 55at% or more, and still more preferably 60at% or more. When the Si concentration is within this range, the amount of oxide near the surface is reduced, and the capacity of the anode material can be improved. The Si concentration is preferably 80at% or less, more preferably 90at% or less, and even more preferably 99at% or less. By having the Si concentration within this range, it is not necessary to excessively prepare equipment or a process for preventing oxidation of silicon particles, the capacity of the anode material can be increased, and the reduction in productivity can be suppressed.
(O concentration)
The O concentration is preferably 46at% or less, more preferably 40at% or less, and still more preferably 30at% or less. When the O concentration is within this range, the amount of oxide near the surface is reduced, and the capacity of the anode material can be increased. The O concentration is preferably 20at% or more, more preferably 10at% or more, and even more preferably 1at% or more. By having the O concentration within this range, it is not necessary to excessively prepare equipment or a process for preventing oxidation of silicon particles, the capacity of the anode material can be increased, and a decrease in productivity can be suppressed.
(thickness of oxide layer)
The thickness of the oxide layer 33B of the silicon particles 33 is preferably 2.1 a or less, more preferably 1.8 a or less, and further preferably 1.3 a or less. When the thickness of the oxide layer 33B is within this range, the amount of oxide near the surface is reduced, and the capacity of the anode material can be increased. The thickness of the oxide layer 33B is preferably 0.7 a or more, more preferably 0.3 a or more, and even more preferably 0.06 a or more. When the thickness of the oxide layer 33B is within this range, it is not necessary to prepare excessively pure Si, and the capacity of the anode material can be increased while suppressing a decrease in productivity. The thickness of the oxide layer 33B can be calculated as follows: siO from the surface layer when measured by X-ray photoelectron spectroscopy 2 Ratio of Si amount of Si2p to Si amount of Si2p from elemental silicon (Si amount of Si2p from elemental silicon to Si from SiO) 2 The inverse of the Si amount ratio of Si2 p), the depth of escape of photoelectrons of Si2p is multiplied by 6 angstroms, thereby calculating the thickness of the oxide layer 33B.
(characteristics of silicon particles according to volume average particle diameter)
Next, characteristics of the silicon particles 33 according to the volume average particle diameter will be described.
(volume average particle diameter)
Hereinafter, the volume average particle diameter (volume-based average particle diameter) of the silicon particles 33 measured by the laser diffraction scattering method is described as a volume average particle diameter.
(volume ratio of oxide layer according to volume average particle diameter)
When the volume is calculated by assuming that the silicon particles 33 are spherical and using the volume average particle diameter, the ratio of the volume of the oxide layer 33B to the total volume of the silicon particles 33 is taken as the volume ratio of the oxide layer 33B according to the volume average particle diameter. In this case, the volume ratio of the oxide layer 33B according to the volume average particle diameter is preferably 0.05% or less, more preferably 0.04% or less, and still more preferably 0.035% or less. When the volume ratio is within this range, the amount of oxide near the surface is reduced, and the capacity of the anode material can be improved. The volume ratio of the oxide layer 33B according to the volume average particle diameter is preferably 0.015% or more, more preferably 0.01% or more, and still more preferably 0.001% or more. By having the volume ratio within this range, it is not necessary to excessively prepare equipment or a process for preventing oxidation of silicon particles, the capacity of the anode material can be increased, and the reduction in productivity can be suppressed.
The volume ratio of the oxide layer 33B according to the volume average particle diameter can be calculated as follows. That is, the volume of the silicon particles 33 is calculated assuming that the silicon particles 33 are spherical (true sphere), and using the volume average particle diameter as the diameter of the silicon particles 33. Next, the thickness of the oxide layer 33B calculated as described above is subtracted from the volume average particle diameter to calculate the diameter of the Si layer 33A, the Si layer 33A is assumed to be spherical (true sphere), and the volume of the Si layer 33A is calculated using the diameter of the Si layer 33A. The volume of the oxide layer 33B is a value obtained by subtracting the volume of the Si layer 33A from the volume of the silicon particles 33 thus calculated. Next, the ratio of the volume of the oxide layer 33B to the volume of the silicon particles 33 is taken as the volume ratio of the oxide layer 33B according to the volume average particle diameter.
(characteristics of silicon particles according to D50)
Next, characteristics of the silicon particles 33 according to D50 will be described.
(D50)
The particle diameter with a cumulative frequency of 50 vol% in the volume-based particle size distribution measured by the laser diffraction scattering method was set as D50.
(volume ratio of oxide layer according to D50)
Here, in the case where the silicon particles 33 are assumed to be spherical and the volume is calculated using D50, the ratio of the volume of the oxide layer 33B to the total volume of the silicon particles 33 is taken as the volume ratio of the oxide layer 33B according to D50. In this case, the volume ratio of the oxide layer 33B according to D50 is preferably 0.4% or less, more preferably 0.3% or less, and further preferably 0.25% or less. When the volume ratio is within this range, the amount of oxide near the surface is reduced, and the capacity of the anode material can be improved. The volume ratio of the oxide layer 33B according to D50 is preferably 0.13% or more, more preferably 0.05% or more, and still more preferably 0.01% or more. By having the volume ratio within this range, it is not necessary to excessively prepare equipment or a process for preventing oxidation of silicon particles, the capacity of the anode material can be increased, and the reduction in productivity can be suppressed.
The volume ratio of the oxide layer 33B according to D50 can be calculated as follows. That is, the volume of the silicon particles 33 is calculated assuming that the silicon particles 33 are spherical (true sphere), and using D50 as the diameter of the silicon particles 33. Next, the thickness of the oxide layer 33B calculated as described above is subtracted from D50 to calculate the diameter of the Si layer 33A, the Si layer 33A is assumed to be spherical (true sphere), and the volume of the Si layer 33A is calculated using the diameter of the Si layer 33A. The volume of the oxide layer 33B is a value obtained by subtracting the volume of the Si layer 33A from the volume of the silicon particles 33 thus calculated. Next, the ratio of the volume of the oxide layer 33B to the volume of the silicon particles 33 is taken as the volume ratio of the oxide layer 33B according to D50.
(cathode)
The positive electrode 16 shown in fig. 1 includes a current collecting layer and a positive electrode material layer. The current collecting layer of the positive electrode 16 is a layer made of a conductive material, and examples of the conductive material include aluminum. The positive electrode material layer is a layer of positive electrode material, and is provided on the surface of the current collecting layer of the positive electrode 16. The thickness of the current collecting layer of the positive electrode may be, for example, about 10 μm or more and 30 μm or less, and the thickness of the positive electrode material layer may be, for example, about 10 μm or more and 100 μm or less.
The positive electrode material layer contains a positive electrode material. The positive electrode material contains particles of a lithium compound that is a lithium-containing compound. The lithium compound may be a lithium-containing metal oxide, a lithium-containing phosphate, or the like. More specifically, examples of the lithium compound include LiCoO 2 、LiNiO 2 、LiMnO 2 、LiMn 2 O 4 、LiNi a Co b Mn c O 2 (wherein 0 < a < 1, 0 < b < 1, 0 < c < 1, a+b+c=1), liFePO 4 Etc. The lithium compound may contain only one material or two or more materials. The positive electrode material layer may contain a substance other than the positive electrode material, for example, a binder. The binder may be any material, and examples thereof include polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PAA, and the like. The binder may be used alone or in combination of two or more.
(separator)
The separator 18 shown in fig. 1 is an insulating member. In the present embodiment, the separator 18 is a porous film made of resin, for example, and examples of the resin include Polyethylene (PE) and polypropylene (PP). The separator 18 may be formed by stacking films of different materials. The separator 18 may have a heat-resistant layer. The heat-resistant layer is a layer containing a substance having a high melting point. The heat-resistant layer may contain particles of an inorganic material such as alumina, for example.
(electrolyte)
The electrolyte provided in the battery 1 is a nonaqueous electrolyte. The electrolyte is impregnated into the voids within the electrode assembly 12. The electrolyte solution contains, for example, a lithium salt and an aprotic solvent. The lithium salt is dispersed and dissolved in an aprotic solvent. Examples of the lithium salt include LiPF 6 、LiBF 4 、Li[N(FSO 2 ) 2 ]、Li[N(CF 3 SO 2 ) 2 ]、Li[B(C 2 O 4 ) 2 ]、LiPO 2 F 2 Etc. The aprotic solvent may be, for example, a mixture of cyclic carbonates and chain carbonates. Examples of the cyclic carbonate include EC, PC, and butenyl carbonate. Examples of the chain carbonate include dimethyl carbonate (DMC), ethylmethyl carbonate (EMC), and diethyl carbonate (DEC).
(method for manufacturing Battery)
Next, an example of a method for manufacturing the battery 1 according to the present embodiment will be described. The manufacturing method comprises the following steps: a step of preparing a silicon raw material in an atmosphere having an oxygen concentration of 5% or less; a step of manufacturing a negative electrode material by using a silicon raw material and disposing tungsten trioxide and a silicon material on the surface of carbon; and a step of manufacturing a positive electrode material.
(step of preparing silicon raw material)
Fig. 8 is a flowchart illustrating steps for preparing a silicon feedstock. The silicon raw material is a raw material of silicon particles 33. As shown in fig. 8, the steps for preparing the silicon raw material include a crushing step S1, a coarse crushing step S2, and a crushing step S3.
The step of preparing the silicon raw material preferably comprises pulverizing the silicon base material in an atmosphere having an oxygen concentration of 5% or less to prepare the silicon raw material, more preferably having an oxygen concentration of 3% or less, still more preferably having an oxygen concentration of 1% or less, and still more preferably having an oxygen concentration of 0.1% or less. By making the oxygen concentration so low, oxidation of the nascent surface of silicon occurring after crushing and further thickening of the thickness of the oxide layer formed on the surface before crushing are suppressed, whereby reduction in capacity can be suppressed. The oxygen concentration may be measured by an oxygen monitor OM-25MF01 manufactured by Tagrong engineering, inc., or by a low-concentration oxygen monitor JKO-O2LJD3 manufactured by ICHINEN, inc. if the oxygen concentration is lower than 1%. Further, the oxygen concentration is preferably set in the above range in the coarse grinding step S2 and the grinding step S3, and more preferably set in the above range in all of the grinding step S1, the coarse grinding step S2, and the grinding step S3.
(crushing step)
The crushing step S1 is a step of crushing a silicon cake to obtain a silicon crushed material. The size of the silicon block is not particularly limited. The shape of the silicon block is not particularly limited, and may be, for example, columnar, plate-like, or granular. As the silicon ingot, a silicon ingot, polycrystalline silicon other than the ingot, monocrystalline silicon, columnar silicon ingot, a silicon wafer for a monitor, a silicon wafer for a dummy, or granular silicon can be used.
As the crushing device for crushing the silicon cake, there is no particular limitation, and for example, a hammer crusher, a jaw crusher, a gyratory crusher, a cone crusher, a roller crusher, an impact crusher may be used. Regarding the size of the silicon crushed material obtained by crushing the silicon lump, the longest diameter is preferably in the range of more than 1mm and 5mm or less.
(coarse pulverizing step)
The coarse grinding step S2 is a step of coarsely grinding the silicon crushed material to obtain coarse silicon particles. The coarse silicon particles obtained in the coarse grinding step S2 preferably have a maximum particle diameter of 1000 μm or less, which is separated by sieving. Therefore, the coarse grinding step S2 preferably includes a step of classifying the coarse powder obtained by coarse grinding with a sieve having 1000 μm holes, and collecting coarse particles having a maximum particle diameter of 1000 μm or less. If the size of the coarse silicon particles is larger than 1000 μm, the coarse silicon particles may not be sufficiently crushed and mixed into the particles in the subsequent crushing step S3. The maximum particle size of the coarse silicon particles is particularly preferably 500 μm or less.
The coarse grinding may be performed in either a dry or wet manner, and is preferably performed in a dry manner. The pulverizing device for coarsely pulverizing the silicon pulverized material is not particularly limited, and for example, a ball mill (planetary ball mill, vibration ball mill, rolling ball mill, agitator ball mill), jet mill, or three-dimensional ball mill may be used.
(pulverization step)
The grinding step S3 is a step of grinding coarse silicon particles to obtain a silicon raw material (silicon fine particles). In the pulverizing step S3, for example, a ball mill (planetary ball mill, vibration ball mill, rolling ball mill, agitator ball mill), a jet mill, or a three-dimensional ball mill can be used. As the pulverizing device, a three-dimensional ball mill manufactured by Nagao System Co., ltd.) is preferably used.
As the hard spheres, zirconia (ZrO 2 ) Balls or alumina (Al) 2 O 3 ). The particle diameter of the hard spheres is preferably in the range of 0.1mm to 20 mm. If the particle diameter of the hard spheres is within this range, coarse silicon particles can be efficiently crushed. The amount of the hard spheres used is preferably in the range of 500 parts by mass to 2500 parts by mass with respect to 100 parts by mass of the coarse silicon particles. If the amount of the hard spheres used is within this range, coarse silicon particles can be efficiently crushed. The amount of the hard balls to be used is more preferably in the range of 1000 parts by mass to 2000 parts by mass, particularly preferably in the range of 1100 parts by mass to 1500 parts by mass.
Regarding the filling rate of the coarse silicon particles and the hard balls in the container of the three-dimensional ball mill, the total volume of the coarse silicon particles and the hard balls is preferably in the range of 3% to 35% with respect to the container capacity. If the filling rate is too low, the pulverization efficiency may be lowered, and the production cost may be increased. On the other hand, if the filling ratio is too high, pulverization becomes difficult, and there is a possibility that the average particle diameter of the obtained silicon raw material becomes large or that coarse silicon particles are insufficiently pulverized to remain particles thereof. The filling ratio of the coarse silicon particles and the hard balls is more preferably in the range of 15% to 30%, and particularly preferably in the range of 20% to 30%. The filling rate is a volume when the raw material and the ball are filled into the container without gaps, and the filling rate is assumed to be 100%. For example, if half of the spherical container is filled with the raw material and the hard balls without gaps, it is 50%, and if the raw material and the hard balls are filled to 1/2 of the height of the hemispherical container (one of the two half containers forming the container) without gaps, it is 15.6%. However, the term "no gap" as used herein means a gap in a huge sense, meaning a state where a plurality of balls are absent, not a gap formed between balls.
The container is preferably filled with a non-oxidizing gas. By using a container filled with a non-oxidizing gas, aggregation of particles and oxidation of silicon particles due to moisture absorption of the silicon particles can be suppressed. As the non-oxidizing gas, argon, nitrogen, and carbon dioxide may be used.
In the method for producing a silicon raw material according to the present embodiment, coarse silicon particles having a maximum particle diameter of 1000 μm or less as measured by a sieving method are prepared in the coarse grinding step S2, and the coarse silicon particles are ground under specific conditions using a three-dimensional ball mill in the subsequent grinding step S3. Therefore, it is possible to industrially advantageously produce a silicon raw material which is fine, hardly forms coarse agglomerated particles, and has high dispersibility when mixed with other raw material particles.
The method for producing the silicon raw material is described above, but the production method is not limited to the above method, and may be any method.
(step of producing negative electrode Material and Positive electrode Material)
Fig. 9 is a flowchart illustrating an example of a method for manufacturing a battery according to the present embodiment. As shown in fig. 9, the present manufacturing method forms the negative electrode 14 through the steps of step S10 to step S28.
Specifically, WO is added to the dissolution solution 3 Raw materials, WO 3 The raw material is dissolved in the dissolution solution (step S10; dissolution step). WO (WO) 3 The raw material is tungsten trioxide used as a raw material of the negative electrode material. The dissolving solution is capable of dissolving WO 3 The raw material, namely, a solution of tungsten trioxide. For example, an alkaline solution is used as the dissolution solution, and an aqueous ammonia solution is used in the present embodiment. The concentration of ammonia in the dissolving solution is preferably 5% to 30% by weight based on the entire dissolving solution.
In the present embodiment, the dissolution is not limited to a state of complete dissolution, but includes a state of partial residue. And, the dissolution includes mixed dissolution.
WO 3 The starting materials being obtained, e.g. by reacting CaWO 4 After the reaction with hydrochloric acid, the solution is dissolved in ammonia and the crystallized ammonium paratungstate is fired, but the solution may be produced by any method. In addition, WO 3 Tungsten trioxide, tungsten oxide (VI), anhydrous tungstic acid.
In step S10, WO is applied to the amount of ammonia contained in the dissolving solution 3 The ratio of the amount of the raw material to be added is preferably 1% to 10% by mol%. By WO 3 The ratio of the addition amount of the raw material is 1% or more, so that the amount of tungsten trioxide in the solution for dissolution can be made sufficient, and WO can be used 3 The ratio of the addition amount of the raw material is 10% or less, and the amount of tungsten trioxide remaining undissolved can be suppressed. In step S10, WO is added to the dissolution solution 3 Stirring the raw materials for a predetermined time to obtain WO 3 The raw material is dissolved in a dissolving solution. The predetermined time is preferably 6 hours or more and 24 hours or less. WO is made by setting the prescribed time to 6 hours or longer 3 The raw material is properly dissolved in the dissolution solution, and the predetermined time is set to 24 hours or less, whereby the production time can be suppressed from becoming excessively long. The step S10 may be performed as a step described laterS12 is prepared in advance to be dissolved with WO 3 Preparing a solution for dissolving the raw material.
Next, a silicon raw material is added to a solution containing WO 3 The raw material is dissolved in a solution for dissolving (in this case, an ammonium tungstate solution) (step S12; adding step).
In step S12, WO is dissolved by stirring 3 A solution for dissolving the raw material and dispersing the silicon raw material in the solution for dissolving. And, in order to promote the silicon raw material and WO in step S12 3 Can be dispersed with silicon raw material and WO 3 Surfactant is added to the solution for dissolution. As the surfactant, sodium Dodecyl Sulfate (SDS) may be used, or a surfactant containing no Na may be used.
As the Na-free surfactant, for example, poly (oxyethylene) alkyl ether, polyoxyethylene nonylphenyl ether, and the like can be used. As the poly (oxyethylene) alkyl ether, a substance having an alkyl group having 12 to 15 carbon atoms is preferably used, and for example, C can be used 12 H 25 O(C 2 H 4 ) n H (poly (oxyethylene) dodecyl ether), C 13 H 27 O(C 2 H 4 ) n H (Poly (oxyethylene) tridecyl ether), C 13 H 27 O(C 2 H 4 ) n H (Poly (oxyethylene) isotridecyl ether), C 14 H 25 O(C 2 H 4 ) n H (Poly (oxyethylene) tetradecyl ether), C 155 H 25 O(C 2 H 4 ) n H (poly (oxyethylene) pentadecyl ether), and the like. Where n is an integer of 1 or more. As polyoxyethylene nonylphenyl ether, for example, C can be used 9 H 19 C 6 (CH 2 CH 2 O) 8 H、C 9 H 19 C 6 (CH 2 CH 2 O) 10 H、C 9 H 19 C 6 (CH 2 CH 2 O) 12 H, etc.
The addition amount of the surfactant is relative to WO 3 The amount of the raw material added to the dissolution solution is preferably 2% to 8% by weight. By setting to the numerical rangeIn, properly promote the silicon raw material and WO 3 Is a group of (a) and (b) has affinity for a substance.
Next, a primary intermediate material is produced by removing the liquid component of the dissolution solution (primary intermediate material producing step). In the present embodiment, steps S14 and S16 are performed as one intermediate material step. Specifically, the dissolution solution is dried to produce a primary intermediate (step S14; drying step). In step S14, the dissolution solution is dried at 80 ℃ for 12 hours in the atmosphere or in an inert gas, and the liquid component contained in the dissolution solution is removed, that is, evaporated. By using an inert gas, oxidation of Si can be suppressed. The primary intermediate may be said to contain a solid component remaining after the liquid component of the dissolution solution is removed.
Next, the dried primary intermediate is subjected to a heat treatment to produce a primary intermediate material (step S16; heating step). By heating the primary intermediate, a silicon particle 33 having WO provided on its surface is formed 3 Primary intermediate material of particles 32. The primary intermediate is preferably heated at a temperature of 500 ℃ to 900 ℃ in an inert gas. By making the heating temperature of the primary intermediate within this range, the primary intermediate material can be formed appropriately. The heating time of the primary intermediate is preferably 1 hour or more and 10 hours or less. By setting the heating time of the primary intermediate within this range, the primary intermediate material can be formed appropriately. The steps S12 to S16 may be prepared as the preparation step of preparing the primary intermediate material (or primary intermediate) in advance before proceeding to step S18 described later.
Next, the primary intermediate and the carbon raw material (hard carbon in this case) are mixed and dispersed in a liquid (water in this case) (step S18; adding step). The carbon raw material is hard carbon used as a raw material.
The carbon raw material can be produced by, for example, an oil furnace method. In the oil furnace method, for example, a raw material oil is sprayed in a high-temperature atmosphere, and is thermally decomposed and then quenched to produce a particulate carbon raw material. However, the method for producing the carbon raw material is not limited thereto, and any method may be used.
Here, the solvent is used for dissolvingWO is added into the liquid 3 When the raw materials are a raw material, a silicon raw material and a carbon raw material, the process will be described in WO 3 The ratio of the addition amount of the silicon raw material to the total amount of the addition amounts of the silicon raw material and the addition amount of the carbon raw material is referred to WO as the silicon raw material addition ratio 3 WO in terms of the total amount of the addition amount of the raw material, the addition amount of the silicon raw material, and the addition amount of the carbon raw material 3 Ratio of the addition amount of raw materials as WO 3 Raw material addition ratio. In the present production method, the silicon raw material addition ratio is set to 1% by weight or more and 10% by weight or less, preferably 2% by weight or more and 8% by weight or less, and more preferably 5% by weight or more and 8% by weight or less. When the silicon raw material addition ratio is within this range, the silicon particles 33 can be formed appropriately on the surfaces of the carbon particles 30, and the capacity of the battery can be improved as a negative electrode. In the present production method, WO is used 3 The raw material addition ratio is set to 1% by weight or more and 10% by weight or less, preferably 2% by weight or more and 8% by weight or less, and more preferably 5% by weight or more and 8% by weight or less. By WO 3 The ratio of the raw material to be added is within this range, WO can be formed on the surface of the carbon particles 30 appropriately 3 The particles 32, which are the negative electrode, can increase the capacity of the battery.
In step S18, the liquid (here, water) is stirred to disperse the primary intermediate material and the carbon raw material in the liquid. In step S18, the carbon raw material, silicon and WO are raised 3 A surfactant may be added to the liquid. As the surfactant, sodium Dodecyl Sulfate (SDS) may be used, or a surfactant containing no Na may be used. The amount of the surfactant to be added is preferably 2% to 8% by weight based on the amount of the carbon raw material to be added to the liquid. By setting the value within the range, the carbon raw material, silicon and WO are properly promoted 3 Is a group of (a) and (b) has affinity for a substance.
Next, the negative electrode material is produced by removing the liquid component of the solution in which the primary intermediate material and the carbon raw material are dispersed in the liquid (negative electrode material producing step). In the present embodiment, steps S20 and S22 are executed as the negative electrode material generating step. Specifically, the solution is dried to produce a negative electrode intermediate (step S20; drying step). In step S20, the liquid component contained in the solution is removed, that is, evaporated, by drying the solution at 80 ℃ for 12 hours in the atmosphere or in an inert gas. The negative electrode intermediate may be said to contain a solid component remaining after the liquid component of the solution is removed.
Next, the anode material is produced by heating the anode intermediate (step S22; heating step). By heating the anode intermediate, a coating of WO is formed on the surface of the carbon particles 30 3 Negative electrode materials of particles 32 and silicon particles 33. The heating temperature of the negative electrode intermediate is preferably 500 ℃ or higher and 900 ℃ or lower in an inert gas. By setting the heating temperature of the anode intermediate within this range, the anode material can be formed appropriately. The heating time of the negative electrode intermediate is preferably 1 hour or more and 10 hours or less. By setting the heating time of the anode intermediate within this range, the anode material can be formed appropriately.
Next, the negative electrode 14 is formed using the formed negative electrode material (step S24). That is, the negative electrode 14 is formed by forming the negative electrode material layer 22 containing the negative electrode material on the surface of the current collecting layer 20.
The present manufacturing method forms the positive electrode 16 (step S26). In step S26, a positive electrode material is formed by the same method as in steps S10 to S24, except that a lithium compound raw material, that is, a lithium compound raw material, is used instead of a carbon raw material. Next, a positive electrode material layer containing a positive electrode material is formed on the surface of the current collecting layer for the positive electrode 16, thereby forming the positive electrode 16.
After the negative electrode 14 and the positive electrode 16 are formed, the battery 1 is manufactured using the negative electrode 14 and the positive electrode 16 (step S28). Specifically, the negative electrode 14, the separator 18, and the positive electrode 16 are laminated to form the electrode group 12, and the electrode group 12 and the electrolyte are contained in the case 10, thereby manufacturing the battery 1.
As described above, in this embodiment, as shown in steps S10 to S24, the liquid component is removed after adding silicon to the solution for dissolution in which tungsten trioxide is dissolved, to thereby produce the primary intermediate material, and then the primary intermediate material and hard carbon are added to the liquid, and then the liquid component is removed, to thereby produce the negative electrode material. Hereinafter, the method for producing such a negative electrode material will be appropriately described as a solution method. The above production method using SDS as a surfactant is referred to as a first production method.
In step S18, in order to upgrade the carbon feedstock, silicon and WO 3 A surfactant may be added to the solution. As the surfactant, a surfactant containing no Na can be used. As shown in steps S10 to S24, a negative electrode material is produced by adding silicon to a solution for dissolution in which tungsten trioxide is dissolved, removing a liquid component to produce a primary intermediate material, adding the primary intermediate material and hard carbon to the liquid, and removing the liquid component. Hereinafter, the method for producing such a negative electrode material will be appropriately described as a solution method. The above manufacturing method is referred to as a second manufacturing method.
(modification of the method for manufacturing a Battery)
Next, another example of the method for manufacturing the battery 1 according to the present embodiment will be described. Fig. 10 is a flowchart illustrating an example of a method for manufacturing a battery according to the present embodiment. As shown in fig. 10, the present manufacturing method forms the negative electrode 14 through the steps of step S30 to step S44. Step S30, step S32, step S40, step S42, and step S44 perform the same processing as step S10, step S12, step S24, step S26, and step S28.
Next, to be dissolved with WO 3 The raw material and the silicon raw material are dissolved by adding a carbon raw material to the solution for dissolving the raw material and the silicon raw material (step S34; adding step). The carbon raw material is hard carbon used as a raw material.
In step S34, the dissolution solution is stirred to thereby cause WO 3 The raw materials, silicon raw materials and carbon raw materials are mixed and dispersed in a solution. In step S34, the carbon raw material, silicon and WO are raised 3 A surfactant may be added to the solution.
Next, a negative electrode material is produced by removing the liquid component of the dissolution solution (negative electrode material producing step). In the present embodiment, as the anode material generating step, steps S36 and S38 are performed. Specifically, the dissolution solution is dried to produce a negative electrode intermediate (step S36; drying step). In step S36, the dissolution solution is dried at 80 ℃ for 12 hours in the atmosphere or in an inert gas, and the liquid component contained in the dissolution solution is removed, that is, evaporated. The negative electrode intermediate may be said to contain a solid component remaining after the liquid component of the dissolution solution is removed.
Next, a negative electrode material is produced by heating the negative electrode intermediate (step S38; heating step). By heating the anode intermediate, a coating of WO is formed on the surface of the carbon particles 30 3 Negative electrode materials of particles 32 and silicon particles 33. The heating temperature of the negative electrode intermediate is preferably 500 ℃ or higher and 900 ℃ or lower in an inert gas. By setting the heating temperature of the anode intermediate within this range, the anode material can be formed appropriately. The heating time of the negative electrode intermediate is preferably 1 hour or more and 10 hours or less. By setting the heating time of the anode intermediate within this range, the anode material can be formed appropriately.
As described above, in the present embodiment, as shown in steps S30 to S44, silicon and hard carbon are added to the solution for dissolution in which tungsten trioxide is dissolved, and then the liquid component is removed, thereby manufacturing the negative electrode material. Hereinafter, the method for producing such a negative electrode material is also appropriately referred to as a solution method. The above manufacturing method is referred to as a third manufacturing method.
The method for producing the negative electrode material and the positive electrode material is described above, but the production method is not limited to the above method, and may be any method.
(Effect)
As described above, the anode material according to the present embodiment is an anode material of a battery, and includes carbon, tungsten trioxide, and silicon particles 33 containing silicon. In the case of measuring the silicon particles 33 by X-ray photoelectron spectroscopy, the Si amount of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p is 3 or more based on the atomic concentration.
Here, if tungsten trioxide and Si are provided in the anode material, the performance of the battery can be improved. However, as a result of intensive studies, the present inventors have found that Si oxide suppressing capacity is required to further improve the performanceIs improved. In contrast, in the anode material according to the present embodiment, the Si content of Si2p derived from elemental silicon and SiO derived from the surface layer 2 The Si content ratio of Si2p is 3 or more based on the atomic concentration. That is, according to the present embodiment, the performance of the battery can be improved by reducing silicon oxide.
When the silicon particles 33 are measured by X-ray photoelectron spectroscopy, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer is 1.2 or more based on the atomic concentration. In the negative electrode material according to the present embodiment, the ratio of the Si amount of Si2p to the O amount of O1s in the silicon particles 33 falls within this range, so that the amount of oxide near the surface is reduced, and the performance of the battery can be improved. In particular SiO 2 In such a case, the ratio of Si amount of Si2p to O amount of O1s is within the above range, so that SiO may function as a factor for suppressing the capacity increase 2 The amount of silicon oxide other than silicon oxide is also reduced, and the performance of the battery can be suitably improved.
The silicon particles 33 include a Si layer 33A made of Si and an oxide layer 33B made of silicon oxide formed on the surface of the Si layer 33A, and when the silicon particles 33 are assumed to be spherical and the volume of the silicon particles 33 is calculated using the volume average particle diameter, the volume of the oxide layer 33B is 0.05% or less of the total volume of the silicon particles 33. When the volume ratio of the oxide layer 33B is within this range, the amount of oxide near the surface is reduced, and the performance of the battery can be improved.
The silicon particles 33 include a Si layer 33A made of Si and an oxide layer 33B made of silicon oxide formed on the surface of the Si layer 33A, and when the volume of the silicon particles 33 is calculated using a particle size D50 having a cumulative frequency of 50 vol% in a volume-based particle size distribution measured by a laser diffraction scattering method assuming that the silicon particles 33 are spherical, the volume of the oxide layer 33B is 0.4% or less of the total volume of the silicon particles 33. When the volume ratio of the oxide layer 33B is within this range, the amount of oxide near the surface is reduced, and the performance of the battery can be improved.
Further, in the negative electrode material, when the total content of carbon, tungsten trioxide, and silicon particles 33 is set to 100 wt%, the content of silicon particles 33 is preferably 1 wt% or more and 10 wt% or less. By making the content of the silicon particles 33 within this range, the performance of the battery can be improved.
The method for producing a negative electrode material according to the present embodiment includes: a step of preparing a silicon raw material in an atmosphere having an oxygen concentration of 5% or less; and a step of using a silicon raw material to generate a negative electrode material containing carbon, tungsten trioxide and silicon particles 33, wherein when the silicon particles 33 are measured by X-ray photoelectron spectroscopy, the Si content of Si2p of elemental silicon and SiO derived from the surface layer 2 The Si content ratio of Si2p is preferably 3 or more based on the atomic concentration. By preparing the silicon raw material in this manner at a low oxygen concentration, oxidation of silicon can be suppressed, and the performance of the battery can be improved.
Example (example)
Next, examples will be described.
Example 1
(preparation of silicon feedstock)
The scaly polysilicon masses (purity: 99.999999999% by mass, length: 5 to 15mm, width: 5 to 15mm, thickness: 2 to 10 mm) were crushed using a hammer mill. Subsequently, the obtained crushed material was dry-classified using a sieve having 5mm openings, to obtain an undersize silicon crushed material.
The obtained silicon crushed material, hard spheres (zirconia spheres, diameter: 10 mm) and a container which can be divided into one container and another container were each contained in an Ar-filled glove box. In the glove box, 30 parts by mass of silicon crushed material and 380 parts by mass of hard balls were put into one of the containers. Next, one container into which the silicon crushed material and the hard ball were put was combined with the other container, and the two containers were tightly sealed in a glove box filled with Ar. The interface of the two containers is a slip fit surface that maintains an airtight seal. The filling rate of the silicon crushed material and the hard balls in the container was 28%.
The container filled with the silicon crushed material and the hard balls was taken out of the glove box and set in a three-dimensional ball mill. Then, at the rotation speed of the first rotation shaft: 300rpm, rotational speed of the second rotational shaft: 300rpm, pulverizing time: coarse pulverization was performed under the condition of 0.33 hours. The coarsely crushed silicon coarse particles and hard spheres are dry-classified by using a sieve having 1000 μm holes, to obtain coarse silicon particles having a maximum particle diameter of 1000 μm or less.
The obtained coarse silicon particles, hard spheres (zirconia spheres, diameter 10 mm) and hemispherical containers were each contained in an Ar-filled glove box. Next, 15 parts by mass of the silicon crushed material and 200 parts by mass of hard balls (1333 parts by mass of hard balls based on 100 parts by mass of the coarse silicon particles) were put into one of the hemispherical containers in the glove box. Next, one hemispherical container and the other hemispherical container, into which the silicon crushed material and the hard ball are put, were combined so as to form a spherical container, and the two containers were tightly sealed in a glove box filled with Ar. The filling rate of the silicon crushed material and the hard balls in the container was 15%.
The container filled with the coarse silicon particles and the hard balls was taken out of the glove box and set in a three-dimensional ball mill. Then, at the rotation speed of the first rotation shaft: 300rpm, rotational speed of the second rotational shaft: 300rpm, pulverizing time: crushing for 3 hours to obtain the silicon raw material.
(preparation of negative electrode Material)
In example 1, a negative electrode material was produced by a first production method using a solution method described in the embodiment using hard carbon, tungsten trioxide, and silicon. Specifically, 5ml of 28 wt% ammonia solution and 0.05g of WO were added to a 50ml beaker 3 The starting material was stirred at 40℃for 12 hours to give WO 3 The starting material is dissolved in an ammonia solution. And into the ammonia solution to correspond to WO 3 0.05g of SDS was added so that the weight ratio of the raw materials became 1:1, and the mixture was stirred at room temperature for 4 hours to dissolve SDS in an ammonia solution. Next, the ammonia solution is added to the solution to react with WO 3 0.05g of silicon raw material was added so that the weight ratio of the raw materials became 1:1, and the mixture was stirred at room temperature for 4 hours to dissolve the silicon raw material in an ammonia solution. Then, after stirring the ammonia solution, it was dried by heating at 80℃for 12 hours to yield a primary intermediate material. Next, the primary intermediate material was introduced into the tubular furnace and kept at room temperature for 2 hours under a nitrogen atmosphere, after which the continuous addition was performed while keeping the nitrogen atmosphereHeat (heating to 200 ℃ C. At a heating rate of 3 ℃ C./min, heating to 550 ℃ C. At a heating rate of 1 ℃ C./min, heating to 700 ℃ C. At a heating rate of 3 ℃ C./min) and holding for 2 hours to produce an intermediate material. Next, the primary intermediate material thus produced, 5ml of pure water, 0.053g of SDS and 0.95g of carbon raw material were added in this order. Then, the liquid was stirred for 4 hours until the carbon raw material was dispersed in pure water, and then heated at 80 ℃ for 12 hours to dry the liquid, thereby producing a negative electrode intermediate. Next, the negative electrode intermediate was introduced into a tubular furnace, and the furnace was kept at room temperature for 2 hours under a nitrogen atmosphere, and thereafter, continuously heated (heated to 200 ℃ C. At a heating rate of 3 ℃/min, heated to 550 ℃ C. At a heating rate of 1 ℃/min, and heated to 700 ℃ C. At a heating rate of 3 ℃/min) and kept for 2 hours under a nitrogen atmosphere, to produce a negative electrode material.
In example 1, the ratio of the silicon raw material, i.e., the addition amount of the silicon raw material to the carbon raw material, WO 3 The total of the amount of the raw material and the amount of the silicon raw material added was 5% by weight. In example 1, WO 3 The addition amount of the raw material was 0.05g, the addition amount of the silicon raw material was 0.05g, and the addition amount of the carbon raw material was 0.95g.
Example 2
In example 2, a negative electrode material was produced in the same manner as in example 1, except that the final grinding time when the silicon raw material was obtained was set to 6 hours.
Example 3
In example 3, the surfactant used was poly (oxyethylene) alkyl ether (C 12 H 25 O(C 2 H 4 ) n H (poly (oxyethylene) dodecyl ether)) and was produced by the second production method. The amounts of hard carbon, tungsten trioxide, silicon feedstock and surfactant additives were the same as in example 1.
Example 4
In example 4, except that polyoxyethylene nonylphenyl ether (C) 9 H 19 C 6 (CH 2 CH 2 O) 8 H) And the same procedure as in example 3 was repeated except that the final pulverizing time was set to 6 hours when the silicon raw material was obtainedA negative electrode material was produced.
Comparative example 1
In comparative example 1, a negative electrode material was produced in the same manner as in example 1, except that air was filled in the room when the silicon raw material was obtained, and the final pulverization time was set to 1 hour.
Comparative example 2
In comparative example 2, a negative electrode material was produced in the same manner as in example 1, except that air was filled in the room when the silicon raw material was obtained, and the final pulverization time was set to 1.5 hours.
In examples 1 to 4, the oxygen concentration at the time of filling argon into the glove box to obtain the silicon raw material was 5% or less, but in comparative examples 1 and 2, the oxygen concentration at the time of obtaining the silicon raw material was higher than 5% because air was filled into the glove box.
(Properties of silicon particles)
FIG. 11 is a table showing production conditions, characteristics of silicon particles, and evaluation results of each example. As shown in fig. 11, characteristics measured according to XPS were measured for the silicon particles of each example. The Si concentration in FIG. 11 corresponds to the Si concentration described in the present embodiment, the O concentration in FIG. 11 corresponds to the O concentration described in the present embodiment, and the Si concentration in FIG. 11 is derived from SiO 2 The Si concentration ratio of (2) corresponds to the Si concentration ratio derived from SiO described in the present embodiment 2 The Si concentration ratio from Si in FIG. 11 corresponds to the Si ratio from Si described in the present embodiment, and Si/SiO in FIG. 11 2 Si amount corresponding to Si2p from elemental silicon and SiO from the surface layer described in this embodiment 2 The Si/O ratio of (a) Si2p corresponds to the Si ratio of Si2p to O1s in the surface layer described in the present embodiment, and the oxide film thickness of (B) fig. 11 corresponds to the thickness of the oxide layer 33B described in the present embodiment. The X-ray photoelectron spectroscopy of each example uses the apparatus and conditions described in this embodiment.
As shown in fig. 11, characteristics according to the volume average particle diameter and D50 were measured for each example of silicon particles. Silicon particles are put into an aqueous surfactant solution, and the silicon particles are dispersed by ultrasonic treatment to prepare silicon particle dispersionAnd (3) liquid. Subsequently, the particle size distribution of the silicon fine particles in the obtained silicon fine particle dispersion was measured by a laser diffraction scattering particle size distribution measuring apparatus (MT 3300EX II, manufactured by Microtrac Bell). The volume average particle diameter and D50 were obtained from the obtained particle size distribution. SiO of FIG. 11 2 The volume corresponds to the volume of the oxide layer 33B calculated using the volume average particle diameter (or D50) of the present embodiment, the particle volume of fig. 11 corresponds to the volume of the silicon particles 33 calculated using the volume average particle diameter (or D50) of the present embodiment, and the SiO of fig. 11 2 The volume/particle volume corresponds to the volume ratio of the oxide layer 33B according to the volume average particle diameter (or D50) of the present embodiment.
(evaluation results)
As an evaluation of the negative electrode material of each example, the capacity of the negative electrode using the negative electrode material was measured. Specifically, a current value (mAh/g) per 1g at a C ratio of 0.2 and a current value (mAh/g) per 1g at a C ratio of 3.2 were measured. For example, a current value per 1g of negative electrode when the C ratio is 0.2 means a current value that consumes a rated capacity within 0.2 hours.
Further, as an evaluation of the negative electrode material of each example, it was also confirmed whether lithium flowed into or released from Si of the negative electrode. The case where lithium flows into the Si of the negative electrode is x, the case where lithium is not released from the Si of the negative electrode is good, and the case where lithium is not released is x.
The evaluation results are shown in fig. 11. As shown in FIG. 11, it can be seen that Si/SiO 2 In examples 1 and 2 in which the C ratio was 3 or more, since silicon oxide was small, the current value at the C ratio of 0.2 was sufficiently maintained, the current value at the C ratio of 3.2 was sufficiently maintained, and lithium was flowed into the negative electrode and released from the negative electrode, so that the performance of the battery was improved.
On the other hand, it is known that Si/SiO 2 In comparative examples 1 and 2 in which the C ratio was 3.2, the current value was reduced because the silicon oxide was increased, and lithium was not released from Si of the negative electrode, and the performance of the battery was not properly improved.
The embodiments of the present invention have been described above, but the content of the embodiments is not limited to the embodiments. The aforementioned components include components that can be easily assumed by those skilled in the art, substantially the same components, and components within a so-called equivalent range. The above-described components can be appropriately combined. Various omissions, substitutions and changes in the constituent elements may be made without departing from the spirit of the foregoing embodiments.
Symbol description
1 cell
14 negative electrode
22 negative electrode material layer
30 carbon particles
32WO 3 Particles
33 silicon particles

Claims (8)

1. A negative electrode material is a negative electrode material of a battery,
silicon material comprising carbon, tungsten trioxide and silicon,
in the case of measuring the silicon material by X-ray photoelectron spectroscopy, the Si amount of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p is 3 or more based on the atomic concentration.
2. The negative electrode material according to claim 1, wherein,
when the silicon material is measured by X-ray photoelectron spectroscopy, the ratio of the Si amount of Si2p to the O amount of O1s in the surface layer is 1.2 or more based on the atomic concentration.
3. The negative electrode material according to claim 1 or 2, wherein,
the silicon material includes a Si layer made of Si and an oxide layer made of silicon oxide formed on the surface of the Si layer, and when the silicon material is assumed to be spherical and the volume of the silicon material is calculated using the volume average particle diameter, the volume of the oxide layer is 0.04% or less of the total volume of the silicon material.
4. The negative electrode material according to any one of claim 1 to 3, wherein,
the silicon material includes a Si layer formed of Si and an oxide layer formed on the surface of the Si layer and including Si and O, and when the silicon material is assumed to be spherical and the volume of the silicon material is calculated using a particle diameter D50 having a cumulative frequency of 50% by volume in a volume-based particle size distribution measured by a laser diffraction scattering method, the volume of the oxide layer is 0.4% or less of the total volume of the silicon material.
5. The negative electrode material according to any one of claims 1 to 4, wherein,
when the total content of the carbon, the tungsten trioxide and the silicon material is set to 100 wt%, the content of the silicon material is 1 wt% or more and 10 wt% or less.
6. A battery, comprising: the anode material of any one of claims 1 to 5; and a positive electrode material.
7. A method for manufacturing a negative electrode material of a battery, comprising:
a step of preparing a silicon raw material in an atmosphere having an oxygen concentration of 5% or less; a kind of electronic device with high-pressure air-conditioning system
A step of using the silicon raw material to generate a negative electrode material comprising carbon, tungsten trioxide and a silicon material,
in the case of measuring the silicon material by X-ray photoelectron spectroscopy, the Si amount of Si2p from elemental silicon and SiO from the surface layer 2 The Si content ratio of Si2p is 3 or more based on the atomic concentration.
8. A method of manufacturing a battery, comprising: the method for producing a negative electrode material according to claim 7; and a step of manufacturing a positive electrode material.
CN202280025583.6A 2021-04-08 2022-03-18 Negative electrode material, battery, method for producing negative electrode material, and method for producing battery Pending CN117083734A (en)

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PCT/JP2022/012756 WO2022215498A1 (en) 2021-04-08 2022-03-18 Negative-electrode material, battery, method for producing negative-electrode material, and method for producing battery

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