WO2023199543A1 - 複合活物質粒子、電池、および複合活物質粒子の製造方法 - Google Patents

複合活物質粒子、電池、および複合活物質粒子の製造方法 Download PDF

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WO2023199543A1
WO2023199543A1 PCT/JP2022/041392 JP2022041392W WO2023199543A1 WO 2023199543 A1 WO2023199543 A1 WO 2023199543A1 JP 2022041392 W JP2022041392 W JP 2022041392W WO 2023199543 A1 WO2023199543 A1 WO 2023199543A1
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active material
region
composite active
material particles
oxide phase
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French (fr)
Japanese (ja)
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邦彦 峯谷
忠朗 松村
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Panasonic Intellectual Property Management Co Ltd
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Panasonic Intellectual Property Management Co Ltd
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Priority to US18/905,132 priority patent/US20250029987A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0068—Solid electrolytes inorganic
    • H01M2300/0071—Oxides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure relates to composite active material particles, batteries, and methods for manufacturing composite active material particles.
  • Alloy-based materials that can be alloyed with lithium are expected to be used as negative electrode active materials for high-capacity lithium batteries.
  • a typical example of the alloy material is silicon.
  • Patent Document 1 describes a negative electrode active material that includes a lithium silicate phase and silicon particles dispersed in the lithium silicate phase.
  • an oxide phase containing an oxide a plurality of active material domains containing an active material and dispersed in the oxide phase;
  • Composite active material particles comprising: When the region occupying the surface layer of the composite active material particles is defined as a first region, and the region located inside the first region is defined as a second region, the first region includes the oxide phase, The second region includes the oxide phase and the plurality of active material domains, The abundance ratio of oxygen in the first region is higher than the abundance ratio of oxygen in the second region.
  • Composite active material particles are provided.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of composite active material particles in Embodiment 1.
  • FIG. 2 is a cross-sectional view showing a schematic configuration of base particles used in the method for manufacturing composite active material particles in Embodiment 1.
  • FIG. 3 is a flowchart illustrating an example of a method for manufacturing composite active material particles in Embodiment 1.
  • FIG. 4 is a cross-sectional view showing a schematic configuration of a battery according to the second embodiment.
  • FIG. 5 is a cross-sectional view showing the detailed structure of the negative electrode and the negative electrode active material layer.
  • Patent Document 1 discloses that the lithium silicate phase absorbs the expansion and contraction of silicon particles during charging and discharging, thereby improving the cycle characteristics of the battery.
  • a negative electrode active material in which silicon particles are dispersed in a lithium silicate phase as described in Patent Document 1 many silicon particles exist in an exposed state on the outer surface of the negative electrode active material.
  • interfacial contact between the negative electrode active material and the solid electrolyte tends to deteriorate. That is, as the battery is charged and discharged, silicon particles exposed on the outer surface of the negative electrode active material expand and contract, which may cause separation between the negative electrode active material and the solid electrolyte. Dissociation between the negative electrode active material and the solid electrolyte is particularly likely to occur during high-rate charging when the expansion rate of silicon particles is high. When the negative electrode active material and the solid electrolyte separate, the charging efficiency of the battery decreases.
  • the present disclosure has been made in view of the above circumstances, and provides a technique for suppressing a decrease in charging efficiency of a battery using composite active material particles.
  • the composite active material particles according to the first aspect of the present disclosure are: an oxide phase containing an oxide; a plurality of active material domains containing an active material and dispersed in the oxide phase; Composite active material particles comprising: When the region occupying the surface layer of the composite active material particles is defined as a first region, and the region located inside the first region is defined as a second region, the first region includes the oxide phase, The second region includes the oxide phase and the plurality of active material domains, The abundance ratio of oxygen in the first region is higher than the abundance ratio of oxygen in the second region.
  • the active material may include a material that forms an alloy with lithium.
  • the composite active material particles of the present disclosure are particularly useful when the active material includes a material that forms an alloy with lithium.
  • the active material includes at least one member selected from the group consisting of simple silicon and SiO x (0 ⁇ x ⁇ 2). It may contain one.
  • the composite active material particles of the present disclosure are particularly useful when the active material particles include at least one selected from the group consisting of simple silicon and SiO x (0 ⁇ x ⁇ 2).
  • the oxide phase does not need to contain elemental silicon and SiO x (0 ⁇ x ⁇ 2).
  • the composite active material particles of the present disclosure are particularly useful when the oxide phase does not contain elemental silicon and SiO x (0 ⁇ x ⁇ 2).
  • the oxide phase may be amorphous.
  • the composite active material particles of the present disclosure are particularly useful when the oxide phase is amorphous.
  • the oxide phase may include lithium silicate.
  • the composite active material particles of the present disclosure are particularly useful when the oxide phase includes lithium silicate.
  • the lithium silicate has a composition represented by Li 2y SiO (2+y) (0 ⁇ y ⁇ 2). It's okay. According to the above configuration, expansion and contraction of the active material can be significantly absorbed.
  • the elemental ratio of oxygen to silicon in the first region may be 2 or more. According to the above configuration, a decrease in battery charging efficiency can be further suppressed.
  • the elemental ratio of oxygen to silicon in the second region may be 1.5 or less. According to the above configuration, a decrease in battery charging efficiency can be further suppressed.
  • the battery according to the tenth aspect of the present disclosure includes: a positive electrode; a negative electrode; an electrolyte layer located between the positive electrode and the negative electrode; Equipped with The negative electrode includes composite active material particles according to any one of the first to ninth aspects.
  • the electrolyte layer may include a solid electrolyte. According to the above configuration, battery charging efficiency can be improved.
  • the method for manufacturing composite active material particles according to the twelfth aspect of the present disclosure includes: The method includes coating at least a portion of the surface of a base particle having a structure in which a plurality of active material domains containing an active material are dispersed in an oxide phase with a constituent material of the oxide phase.
  • composite active material particles having a structure suitable for suppressing a decrease in battery charging efficiency can be manufactured.
  • a part of the surface of the base particle is coated with the constituent material of the oxide phase by a solid phase method. You may. According to the above configuration, composite active material particles having a structure suitable for suppressing a decrease in battery charging efficiency can be manufactured more easily.
  • the active material includes at least one member selected from the group consisting of simple silicon and SiO x (0 ⁇ x ⁇ 2). May contain one.
  • the method for producing composite active material particles of the present disclosure is particularly useful when the active material contains at least one selected from the group consisting of simple silicon and SiO x (0 ⁇ x ⁇ 2).
  • the elemental ratio of oxygen to silicon in the constituent material may be 2 or more. According to the above configuration, a decrease in battery charging efficiency can be further suppressed.
  • the elemental ratio of oxygen to silicon in the base particles may be 1.5 or less. According to the above configuration, a decrease in battery charging efficiency can be further suppressed.
  • FIG. 1 is a cross-sectional view showing a schematic configuration of composite active material particles 30 in Embodiment 1.
  • Composite active material particles 30 include an oxide phase 31 and a plurality of active material domains 32 .
  • the oxide phase 31 contains an oxide.
  • Active material domain 32 includes active material.
  • the region occupying the surface layer of the composite active material particles 30 is defined as a first region 35, and the region located inside the first region 35 is defined as a second region 36.
  • First region 35 includes oxide phase 31 .
  • the first region 35 includes a part of the oxide phase 31.
  • the second region 36 includes an oxide phase 31 and a plurality of active material domains 32 .
  • the second region 36 includes the remainder of the oxide phase 31 and a plurality of active material domains 32 .
  • the abundance ratio of oxygen in the first region 35 is higher than the abundance ratio of oxygen in the second region 36.
  • the oxygen contained in the first region 35 and the oxygen contained in the second region 36 both originate from the oxide contained in the oxide phase 31. Therefore, the fact that the oxygen abundance ratio in the first region 35 is higher than the oxygen abundance ratio in the second region 36 means that the oxide phase 31 is present in the first region 35 at a higher ratio than in the second region 36. It means that. In other words, it means that the active material domains 32 are unevenly distributed inside the composite active material particles 30. In this way, in the composite active material particles 30 of this embodiment, the amount of active material present in an exposed state on the outer surface 30S of the composite active material particles 30 is suppressed by the first region 35.
  • the abundance ratio of oxygen in the first region 35 and the abundance ratio of oxygen in the second region 36 can be determined by, for example, the following scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX analysis). Desired.
  • SEM-EDX analysis scanning electron microscope-energy dispersive X-ray analysis
  • powder of composite active material particles 30 is pressure-molded together with zinc powder to produce pellets.
  • a cross section of the pellet is prepared by ion milling and observed using a scanning electron microscope (SEM).
  • SEM scanning electron microscope
  • An arbitrary number (for example, 10) of composite active material particles 30 included in the cross-sectional SEM image are selected.
  • a quantitative line scan is performed on the cross sections of the plurality of selected composite active material particles 30 using an energy dispersive X-ray analysis (EDX analysis) device.
  • EDX analysis energy dispersive X-ray analysis
  • the abundance ratio (atom%) of oxygen in the first region 35 and the abundance ratio (atom%) of oxygen in the second region 36 can be calculated for the cross section of each composite active material particle 30, respectively.
  • the oxygen abundance ratio is measured at arbitrary points (for example, five points) in the first region 35, and the average value thereof is calculated.
  • the abundance ratio of oxygen in the first region 35 can be determined.
  • the oxygen abundance ratio is measured at arbitrary points (for example, five points) in the second region 36, and the average value thereof is calculated. By dividing the total calculated value by the number of composite active material particles 30, the abundance ratio of oxygen in the second region 36 can be determined.
  • the abundance ratio of oxygen in the first region 35 is, for example, 44 atom% or more.
  • the abundance ratio of oxygen in the first region 35 may be 50 atom % or more.
  • the upper limit of the oxygen abundance ratio in the first region 35 is not particularly limited. The upper limit is, for example, 63 atom%.
  • the abundance ratio of oxygen in the second region 36 is, for example, less than 50 atom%.
  • the abundance ratio of oxygen in the second region 36 may be 36 atom % or less.
  • the lower limit of the oxygen abundance ratio in the second region 36 is not particularly limited. The lower limit is, for example, 23 atom%.
  • Each of the plurality of active material domains 32 is sufficiently smaller than the composite active material particles 30 and exists uniformly dispersed in the oxide phase 31. Therefore, no matter which direction a quantitative line scan is performed on the cross section of the composite active material particles 30, the abundance ratio of oxygen in the first region 35 and the abundance ratio of oxygen in the second region 36 are approximately constant values. sell.
  • the composite active material particle 30 is a cross section taken through at least one active material domain 32, and there is no active material domain 32 exposed on the outer surface 30S of the composite active material particle 30. It may have a cross section.
  • the first region 35 is a region occupying the surface layer portion of the composite active material particles 30.
  • the surface layer portion of the composite active material particles 30 is, for example, a region within 500 nm from the outer surface 30S of the composite active material particles 30 toward the inside.
  • the shortest straight line connecting the outer surface 30S of the composite active material particle 30 and the center of gravity G of the cross section is defined as a straight line L.
  • the first region 35 may be a region located between the outer surface 30S and a circle whose center is the center of gravity G and whose radius is 90% of the length from the center of gravity G of the straight line L.
  • a portion of the oxide phase 31 is located outside the virtual circle surrounding all the active material domains 32. May exist.
  • the first region 35 may uniformly cover the second region 36. That is, the first region 35 may form the outer surface 30S of the composite active material particle 30. According to the above configuration, the first region 35 further reduces the amount of active material present in an exposed state on the outer surface 30S of the composite active material particles 30. Therefore, even if the active material expands and contracts as the battery is charged and discharged, the separation between the composite active material particles 30 and the first solid electrolyte (described later) in the negative electrode active material layer is further suppressed, resulting in better interfacial contact. maintained.
  • the first region 35 may cover only a portion of the second region 36. That is, the first region 35 may form part of the outer surface 30S of the composite active material particle 30.
  • the thickness of the first region 35 may or may not be uniform.
  • the first region 35 may include active material domains 32 in addition to the oxide phase 31.
  • the first region 35 may be composed only of the oxide phase 31.
  • the first region 35 may include, for example, 100% of the oxide phase 31 in mass proportion to the entire first region 35, excluding unavoidable impurities.
  • the oxide phase 31 may be a continuous phase without clear grain boundaries.
  • the oxide phase 31 may be composed of a first oxide phase 311 and a second oxide phase 312 located inside the first oxide phase 311.
  • the plurality of active material domains 32 may be dispersed in the second oxide phase 312.
  • the first oxide phase 311 is included in the first region 35 .
  • Second oxide phase 312 is included in second region 36 .
  • the first region 35 may be composed of the first oxide phase 311.
  • the second region 36 may be comprised of a second oxide phase 312 and a plurality of active material domains 32.
  • the ratio (M2/M1) of the mass M2 of the second oxide phase 312 to the mass M1 of the active material included in the plurality of active material domains 32 may satisfy 0.5 ⁇ M2/M1 ⁇ 1.
  • the ratio (M4/M3) of the mass M4 of the first oxide phase 311 to the mass M3 of the composite active material particles 30 may satisfy 0.1 ⁇ M4/M3 ⁇ 0.5. By appropriately adjusting the ratio (M4/M3), expansion and contraction of the active material can be significantly suppressed by the first oxide phase 311.
  • the area occupied by the second region 36 may be larger than the area occupied by the first region 35.
  • the oxide phase 31 is a lithium silicate phase
  • lithium silicate contained in the lithium silicate phase does not have electronic conductivity.
  • the area occupied by the second region 36 is larger than the area occupied by the first region 35, sufficient electron conductivity can be ensured by the active material contained in the second region 36.
  • the active material domain 32 includes an active material that has the property of occluding and releasing metal ions.
  • the active material included in the active material domain 32 may include a material that forms an alloy with lithium. Examples of such materials include simple metals that form alloys with lithium, compounds containing metals that form alloys with lithium, and the like. Examples of elemental metals include silicon, tin, germanium, and bismuth. Examples of compounds containing metals that form an alloy with lithium include oxides, carbides, nitrides, silicides, sulfides, and phosphides.
  • the active material domain 32 may include at least one selected from the group consisting of simple silicon and SiO x (0 ⁇ x ⁇ 2) as an active material.
  • the composite active material particles 30 of this embodiment are particularly useful when the active material contains at least one selected from the group consisting of simple silicon and SiO x (0 ⁇ x ⁇ 2).
  • the active material may be simple silicon.
  • the elemental ratio of oxygen to silicon in the first region 35 is 2 or more.
  • the number may be 3 or more. According to the above configuration, a decrease in battery charging efficiency can be further suppressed.
  • the upper limit of the elemental ratio of oxygen to silicon in the first region 35 is not particularly limited. The upper limit is, for example, 5.
  • the elemental ratio of oxygen to silicon in the second region 36 is less than 2. It may be 1.5 or less. According to the above configuration, a decrease in battery charging efficiency can be further suppressed.
  • the lower limit of the elemental ratio of oxygen to silicon in the second region 36 is not particularly limited. The lower limit is, for example, 0.9.
  • the elemental ratio of oxygen to silicon can be determined by the method described above. Specifically, first, according to the method described above, a cross section of an arbitrary number (for example, 10) of composite active material particles 30 is subjected to quantitative line scanning using an energy dispersive X-ray analysis (EDX analysis) device. Implement. From the obtained spectrum, the abundance ratio of oxygen and the abundance ratio of silicon are measured at arbitrary points (for example, 5 points) in the first region 35 for the cross section of each composite active material particle 30, and the elemental ratio of oxygen to silicon is determined. and calculate their average value. By dividing the sum of the calculated values by the number of composite active material particles 30, the elemental ratio of oxygen to silicon in the first region 35 can be determined.
  • EDX analysis energy dispersive X-ray analysis
  • each composite active material particle 30 the abundance ratio of oxygen and the abundance ratio of silicon are measured at arbitrary points (for example, 5 points) in the second region 36, and the elemental ratio of oxygen to silicon is determined. Calculate their average value. By dividing the sum of the calculated values by the number of composite active material particles 30, the elemental ratio of oxygen to silicon in the second region 36 can be determined.
  • the active material domain 32 may be a particle made of a single silicon.
  • the purity of silicon in the silicon particles is not particularly limited, and is, for example, 99% (2N) or higher.
  • the silicon particles may be single crystal silicon particles or polycrystalline silicon particles.
  • the size of the active material domain 32 is not particularly limited.
  • the active material domain 32 may have a nano-order size.
  • the average particle size of the active material domains 32 is, for example, 0.01 ⁇ m or more and 3 ⁇ m or less.
  • the average particle size of the active material domains 32 can be calculated, for example, by the following method. For example, a cross section of the composite active material particles 30 is observed with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), and the area of a specific active material domain 32 in the SEM image or TEM image is calculated by image processing. .
  • the diameter of a circle having an area equal to the calculated area is considered as the diameter of that particular active material domain 32.
  • the diameters of an arbitrary number (for example, 10) of active material domains 32 are calculated, and their average value is regarded as the average particle diameter of the active material domains 32.
  • an active material having a shape that cannot be called a particle may exist as a domain.
  • active material domains 32 have a generally constant size. However, for example, several active material particles may be combined to form a relatively large active material domain 32.
  • the active material domains 32 and the oxide phase 31 (first oxide phase 311) may have a mottled pattern.
  • the shape of the active material domain 32 is also not particularly limited.
  • the active material domain 32 has, for example, a spherical shape, an ellipsoidal shape, a scale-like shape, or the like.
  • the oxide phase 31 does not need to contain silicon or SiO x (0 ⁇ x ⁇ 2).
  • the composite active material particles 30 of this embodiment are particularly useful when the oxide phase 31 does not contain silicon or SiO x (0 ⁇ x ⁇ 2).
  • the oxide phase 31 may be amorphous.
  • amorphous refers to a crystallinity of substantially 0% (specifically, less than 0.1%), and an amorphous halo in an X-ray diffraction spectrum. This means that no crystalline peak is observed.
  • the oxide phase 31 may contain lithium silicate.
  • Composite active material particles 30 of this embodiment are particularly useful when oxide phase 31 contains lithium silicate. This is because lithium silicate has lithium ion conductivity and does not expand during battery charging.
  • the oxide phase 31 may be a lithium silicate phase.
  • Lithium silicate may have a composition represented by Li 2y SiO (2+y) (0 ⁇ y ⁇ 2).
  • oxide phase 31 is a lithium silicate phase
  • a plurality of active material domains 32 are included in the first oxide phase 311 which is a lithium silicate phase.
  • Lithium silicate having such a composition can significantly absorb expansion and contraction of the active material domains 32.
  • the lithium silicate phase may contain a single composition of lithium silicate or may contain multiple compositions of lithium silicate.
  • Lithium silicate may be amorphous. In amorphous lithium silicate, the above-mentioned "y" can take a value other than 1/2, 1, and 2 by compounding lithium silicate with a plurality of compositions.
  • lithium silicates examples include Li 4 SiO 4 , Li 2 SiO 3 , and Li 2 Si 2 O 5 .
  • the lithium silicate may contain at least one selected from the group consisting of Li 4 SiO 4 , Li 2 SiO 3 , and Li 2 Si 2 O 5 .
  • Lithium silicate may include Li 2 SiO 3 .
  • the lithium silicate may be Li 2 SiO 3 .
  • the composition of the first oxide phase 311 may be the same as or different from the composition of the second oxide phase 312.
  • the composite active material particles 30 have an average particle size in the range of 0.1 ⁇ m or more and 30 ⁇ m or less, for example.
  • the average particle size of the composite active material particles 30 can also be measured by the same method as the method of measuring the average particle size of the active material domains 32.
  • the composite active material particles 30 and the first solid electrolyte described below can form a good dispersion state in the negative electrode. This improves the charging and discharging characteristics of the battery. Furthermore, lithium diffusion within the composite active material particles 30 becomes faster. Therefore, the battery can operate at high output.
  • the ratio of the mass of the active material domains 32 to the mass of the composite active material particles 30 is, for example, 30% or more and 70% or less.
  • the method for manufacturing composite active material particles 30 includes at least part of the surface 20S of base particle 20 having a structure in which a plurality of active material domains 32 containing an active material are dispersed in oxide phase 31 using a constituent material of oxide phase 31. Including coating with.
  • FIG. 3 is a flowchart illustrating an example of a method for manufacturing composite active material particles 30.
  • the composite active material particles 30 may be manufactured by each process shown in the flowchart.
  • step S1 base particles 20 having a structure in which a plurality of active material domains 32 containing an active material are dispersed in an oxide phase 31 are prepared (step S1).
  • FIG. 2 is a cross-sectional view showing a schematic configuration of the base particle 20.
  • silicon particles are used as the material for the active material domains 32
  • lithium silicate is used as the material for the oxide phase 31.
  • step S1 is performed as follows. First, silicon powder and lithium silicate powder are prepared. These are mixed at a predetermined ratio to obtain a raw material powder. The raw material powder is processed by a method such as mechanyl alloying. Thereby, base particles 20 are obtained. By treating the base particles 20 using a mesh or sieve with a predetermined opening, a powder of the base particles 20 having a desired average particle size can be obtained.
  • step S2 At least a portion of the surface 20S of the base particle 20 is coated with a constituent material of the oxide phase 31 (step S2).
  • the method of coating at least a portion of the surface 20S of the base particle 20 with the constituent material of the oxide phase 31 (lithium silicate phase) is not particularly limited. Coating may be performed by any of the liquid phase method, gas phase method, or solid phase method.
  • a solid phase method is preferably used because it is easy to handle.
  • the solid phase method include a solid phase reaction method.
  • the liquid phase method include a coprecipitation method, a sol-gel method, and a hydrothermal reaction method.
  • Examples of the gas phase method include sputtering method and CVD method.
  • FIG. 4 is a cross-sectional view showing a schematic configuration of battery 100 in the second embodiment.
  • Battery 100 includes a positive electrode 220, a negative electrode 210, and an electrolyte layer 13.
  • the positive electrode 220 has a positive electrode active material layer 17 and a positive electrode current collector 18.
  • Positive electrode active material layer 17 is arranged between electrolyte layer 13 and positive electrode current collector 18 .
  • the positive electrode active material layer 17 is in electrical contact with the positive electrode current collector 18 .
  • the positive electrode current collector 18 is a member that has the function of collecting power from the positive electrode active material layer 17.
  • Examples of the material for the positive electrode current collector 18 include aluminum, aluminum alloy, stainless steel, copper, and nickel.
  • the positive electrode current collector 18 may be made of aluminum or an aluminum alloy. The dimensions, shape, etc. of the positive electrode current collector 18 can be appropriately selected depending on the use of the battery 100.
  • the positive electrode active material layer 17 includes a positive electrode active material and a solid electrolyte.
  • a material having the property of occluding and releasing metal ions such as lithium ions can be used.
  • As the positive electrode active material lithium-containing transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, transition metal oxysulfides, transition metal oxynitrides, and the like can be used. Examples of lithium-containing transition metal oxides are Li(Ni,Co,Al) O2 , Li(Ni,Co,Mn) O2 , and LiCoO2 .
  • manufacturing costs can be reduced and the average discharge voltage can be increased.
  • the notation "(A, B, C)" in the chemical formula means "at least one selected from the group consisting of A, B, and C.”
  • “(Ni, Co, Al)” is synonymous with “at least one selected from the group consisting of Ni, Co, and Al.” The same applies to other elements.
  • the positive electrode active material has, for example, a particle shape.
  • the shape of the particles of the positive electrode active material is not particularly limited.
  • the shape of the particles of the positive electrode active material may be acicular, spherical, ellipsoidal, or scaly.
  • the median diameter of the particles of the positive electrode active material may be 0.1 ⁇ m or more and 100 ⁇ m or less.
  • the median diameter of the particles of the positive electrode active material is 0.1 ⁇ m or more, the positive electrode active material and the solid electrolyte can form a good dispersion state in the positive electrode 220. As a result, the charging and discharging characteristics of the battery 100 are improved.
  • the median diameter of the positive electrode active material particles is 100 ⁇ m or less, lithium diffusion within the positive electrode active material particles becomes faster. Therefore, the battery 100 can operate at high output.
  • the solid electrolyte of the positive electrode 220 at least one selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte may be used.
  • Oxide solid electrolytes have excellent high potential stability. By using the oxide solid electrolyte, the charging efficiency of the battery 100 can be further improved.
  • 30 ⁇ v1 ⁇ 95 may be satisfied with respect to the volume ratio “v1:100 ⁇ v1” between the positive electrode active material and the solid electrolyte.
  • v1:100 ⁇ v1 the volume ratio “v1:100 ⁇ v1” between the positive electrode active material and the solid electrolyte.
  • the thickness of the positive electrode 220 may be 10 ⁇ m or more and 500 ⁇ m or less. When the thickness of the positive electrode 220 is 10 ⁇ m or more, a sufficient energy density of the battery 100 is ensured. When the thickness of the positive electrode 220 is 500 ⁇ m or less, the battery 100 can operate at high output.
  • the shape of the solid electrolyte included in the positive electrode 220 is not particularly limited.
  • the shape of the solid electrolyte may be, for example, acicular, spherical, or ellipsoidal.
  • the shape of the solid electrolyte may be particulate.
  • the median diameter of the solid electrolyte particles may be 100 ⁇ m or less.
  • the positive electrode active material and the solid electrolyte can form a good dispersion state in the positive electrode 220. Therefore, the charging and discharging characteristics of the battery 100 are improved.
  • volume diameter means the particle diameter when the cumulative volume in the volume-based particle size distribution is equal to 50%.
  • the volume-based particle size distribution is measured, for example, by a laser diffraction measurement device or an image analysis device.
  • the positive electrode active material layer 17 may contain a conductive additive for the purpose of increasing electronic conductivity.
  • conductive aids include graphites such as natural graphite or artificial graphite, carbon blacks such as acetylene black and Ketjen black, conductive fibers such as carbon fibers or metal fibers, carbon fluoride, and metal powders such as aluminum.
  • conductive whiskers such as zinc oxide or potassium titanate, conductive metal oxides such as titanium oxide, and conductive polymer compounds such as polyaniline, polypyrrole, and polythiophene.
  • the electrolyte layer 13 is located between the positive electrode 220 and the negative electrode 210.
  • Electrolyte layer 13 is a layer containing an electrolyte.
  • the electrolyte is, for example, a solid electrolyte having lithium ion conductivity.
  • Electrolyte layer 13 may be a solid electrolyte layer.
  • the solid electrolyte included in the electrolyte layer 13 will be referred to as a second solid electrolyte.
  • the electrolyte layer 13 may include at least one selected from the group consisting of a halide solid electrolyte, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte as the second solid electrolyte. good.
  • the electrolyte layer 13 may have a multilayer structure.
  • the composition of the material of the layer in contact with the negative electrode 210 may be different from the composition of the material of the layer in contact with the positive electrode 220.
  • the layer in contact with the negative electrode 210 may be made of a sulfide solid electrolyte that has excellent reduction resistance.
  • the layer in contact with the positive electrode 220 may be made of a halide solid electrolyte that has excellent oxidation resistance.
  • the shape of the second solid electrolyte included in the electrolyte layer 13 is not particularly limited.
  • the shape of the second solid electrolyte may be, for example, acicular, spherical, or ellipsoidal.
  • the shape of the second solid electrolyte may be particulate.
  • the median diameter of the particles of the second solid electrolyte may be 100 ⁇ m or less.
  • the second solid electrolyte can form a good dispersion state in the electrolyte layer 13. Therefore, the charging and discharging characteristics of the battery 100 are improved.
  • the thickness of the electrolyte layer 13 may be 1 ⁇ m or more and 300 ⁇ m or less. When the thickness of the electrolyte layer 13 is 1 ⁇ m or more, short circuit between the positive electrode 220 and the negative electrode 210 can be reliably prevented. When the thickness of electrolyte layer 13 is 300 ⁇ m or less, battery 100 can operate at high output.
  • the negative electrode 210 includes a negative electrode active material layer 11 and a negative electrode current collector 12.
  • the negative electrode active material layer 11 is arranged between the electrolyte layer 13 and the negative electrode current collector 12.
  • the negative electrode active material layer 11 is in electrical contact with the negative electrode current collector 12 .
  • the negative electrode current collector 12 is a member that has the function of collecting power from the negative electrode active material layer 11.
  • Examples of the material for the negative electrode current collector 12 include aluminum, aluminum alloy, stainless steel, copper, and nickel.
  • Negative electrode current collector 12 may be made of nickel. The dimensions, shape, etc. of the negative electrode current collector 12 can be appropriately selected depending on the use of the battery 100.
  • FIG. 5 is a cross-sectional view showing the detailed configuration of the negative electrode 210 and the negative electrode active material layer 11.
  • Negative electrode active material layer 11 includes composite active material particles 30 of Embodiment 1 as a negative electrode active material.
  • the negative electrode active material layer 11 may further include a solid electrolyte.
  • the solid electrolyte included in the negative electrode active material layer 11 will be referred to as a first solid electrolyte 40.
  • the first solid electrolyte 40 may have a different composition from the oxide contained in the oxide phase 31 in the composite active material particles 30 of the first embodiment.
  • the first solid electrolyte 40 may be at least one selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, a halide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte.
  • the first solid electrolyte 40 may be a sulfide solid electrolyte.
  • the negative electrode active material layer 11 includes the first solid electrolyte 40
  • the active material included in the active material domain 32 of the composite active material particles 30 is silicon particles, silicon Space for particle expansion and contraction is limited. Therefore, from the viewpoint of charging efficiency, it is not easy to use silicon particles directly dispersed in the negative electrode active material layer 11. Therefore, composite active material particles 30 of Embodiment 1 are particularly useful when negative electrode active material layer 11 includes first solid electrolyte 40.
  • Sulfide solid electrolytes include Li 2 SP 2 S 5 , Li 2 S-SiS 2 , Li 2 SB 2 S 3 , Li 2 S-GeS 2 , Li 3.25 Ge 0.25 P 0.75 S 4 , Li 10 GeP 2 S 12 or the like may be used.
  • LiX, Li2O , MOq , LipMOq , etc. may be added to these.
  • the element X in “LiX” is at least one selected from the group consisting of F, Cl, Br, and I.
  • the element M in “MO q " and " Lip MO q " is at least one selected from the group consisting of P, Si, Ge, B, Al, Ga, In, Fe, and Zn.
  • p and q in "MO q " and " Lip MO q " are each independent natural numbers.
  • oxide solid electrolytes examples include NASICON type solid electrolytes represented by LiTi 2 (PO 4 ) 3 and its element substituted products, (LaLi)TiO 3 -based perovskite type solid electrolytes, Li 14 ZnGe 4 O 16 , Li LISICON-type solid electrolytes represented by 4 SiO 4 , LiGeO 4 and their element-substituted products; garnet-type solid electrolytes represented by Li 7 La 3 Zr 2 O 12 and its element-substituted products; Li 3 N and its H-substituted products. , Li 3 PO 4 and its N - substituted product, glass or glass in which materials such as Li 2 SO 4 and Li 2 CO 3 are added to a base material containing Li-BO compounds such as LiBO 2 and Li 3 BO 3 Ceramics etc. can be used.
  • a compound of a polymer compound and a lithium salt can be used.
  • the polymer compound may have an ethylene oxide structure.
  • the polymer compound can contain a large amount of lithium salt, so that the ionic conductivity can be further increased.
  • Lithium salts include LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) 2 , LiN(SO 2 CF 3 )( SO2C4F9 ), LiC ( SO2CF3 ) 3 , etc. may be used.
  • the lithium salt one lithium salt selected from these may be used alone, or a mixture of two or more lithium salts selected from these may be used.
  • the complex hydride solid electrolyte for example, LiBH 4 --LiI, LiBH 4 --P 2 S 5 , etc. can be used.
  • the halide solid electrolyte is represented by, for example, the following compositional formula (1).
  • ⁇ , ⁇ , and ⁇ each independently have a value greater than 0.
  • M includes at least one selected from the group consisting of metal elements and metalloid elements other than Li.
  • X contains at least one selected from the group consisting of F, Cl, Br, and I.
  • the metalloid elements include B, Si, Ge, As, Sb, and Te.
  • Metal elements include all elements included in Groups 1 to 12 of the periodic table except hydrogen, and 13 excluding B, Si, Ge, As, Sb, Te, C, N, P, O, S, and Se. Contains all elements included in groups 1 to 16.
  • Metal elements are a group of elements that can become cations when forming an inorganic compound with a halogen compound.
  • halide solid electrolyte Li3YX6 , Li2MgX4 , Li2FeX4 , Li(Al, Ga, In ) X4 , Li3 (Al, Ga, In) X6 , etc. may be used.
  • Halide solid electrolytes exhibit excellent ionic conductivity.
  • Each of the solid electrolytes described above can be used not only for the negative electrode 210 but also for the solid electrolyte of the positive electrode 220 and the second solid electrolyte of the electrolyte layer 13.
  • the volume ratio of the composite active material particles 30 and the first solid electrolyte 40 in the negative electrode 210 is expressed as "v2:100-v2"
  • the volume ratio v2 of the composite active material particles 30 satisfies 30 ⁇ v2 ⁇ 95. It's okay.
  • 30 ⁇ v2 is satisfied, a sufficient energy density of the battery 100 is ensured.
  • v2 ⁇ 95 is satisfied, the battery 100 can operate at high output.
  • the shape of the first solid electrolyte 40 included in the negative electrode 210 is not particularly limited.
  • the shape of the first solid electrolyte 40 may be, for example, acicular, spherical, or ellipsoidal.
  • the shape of the first solid electrolyte 40 may be particulate.
  • the median diameter of the particles of the first solid electrolyte 40 may be 100 ⁇ m or less.
  • the composite active material particles 30 and the first solid electrolyte 40 can form a good dispersion state in the negative electrode 210. Therefore, the charging and discharging characteristics of the battery 100 are improved.
  • the median diameter of the particles of the first solid electrolyte 40 may be smaller than the median diameter of the composite active material particles 30. Thereby, the composite active material particles 30 and the first solid electrolyte 40 can form a good dispersion state.
  • the thickness of the negative electrode 210 may be 10 ⁇ m or more and 500 ⁇ m or less. When the thickness of the negative electrode 210 is 10 ⁇ m or more, a sufficient energy density of the battery 100 is ensured. When the thickness of the negative electrode 210 is 500 ⁇ m or less, the battery 100 can operate at high output.
  • the negative electrode active material layer 11 may contain a conductive additive 50 for the purpose of increasing electronic conductivity.
  • a conductive aid the materials listed as the conductive aid 50 that may be included in the positive electrode active material layer 17 can be used.
  • At least one selected from the group consisting of the positive electrode active material layer 17, the electrolyte layer 13, and the negative electrode active material layer 11 contains sulfide for the purpose of facilitating transfer of lithium ions and improving the output characteristics of the battery 100. At least one selected from the group consisting of a compound solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, and a complex hydride solid electrolyte may be included.
  • Examples of the sulfide solid electrolyte, oxide solid electrolyte, halide solid electrolyte, polymer solid electrolyte, and complex hydride solid electrolyte include the sulfide solid electrolyte and oxide solid electrolyte listed as the first solid electrolyte 40 of the negative electrode 210; Halide solid electrolytes, polymer solid electrolytes, and complex hydride solid electrolytes can be used.
  • At least one selected from the group consisting of the positive electrode active material layer 17, the electrolyte layer 13, and the negative electrode active material layer 11 contains a non-aqueous electrolyte for the purpose of facilitating transfer of lithium ions and improving the output characteristics of the battery. , gel electrolytes, or ionic liquids.
  • the non-aqueous electrolyte includes a non-aqueous solvent and a lithium salt dissolved in the non-aqueous solvent.
  • the nonaqueous solvent include a cyclic carbonate solvent, a chain carbonate solvent, a cyclic ether solvent, a chain ether solvent, a cyclic ester solvent, a chain ester solvent, and a fluorine solvent.
  • the cyclic carbonate solvent include ethylene carbonate, propylene carbonate, butylene carbonate, and the like.
  • chain carbonate solvents include dimethyl carbonate, ethylmethyl carbonate, diethyl carbonate, and the like.
  • Examples of the cyclic ether solvent include tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane.
  • Examples of chain ether solvents include 1,2-dimethoxyethane and 1,2-diethoxyethane.
  • Examples of the cyclic ester solvent include ⁇ -butyrolactone.
  • Examples of chain ester solvents include methyl acetate.
  • Examples of the fluorine solvent include fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethylmethyl carbonate, and fluorodimethylene carbonate.
  • non-aqueous solvent one non-aqueous solvent selected from these may be used alone, or a mixture of two or more non-aqueous solvents selected from these may be used.
  • the nonaqueous electrolyte may contain at least one fluorine solvent selected from the group consisting of fluoroethylene carbonate, methyl fluoropropionate, fluorobenzene, fluoroethylmethyl carbonate, and fluorodimethylene carbonate.
  • Lithium salts include LiPF 6 , LiBF 4 , LiSbF 6 , LiAsF 6 , LiSO 3 CF 3 , LiN(SO 2 CF 3 ) 2 , LiN(SO 2 C 2 F 5 ) 2 , LiN(SO 2 CF 3 )( SO 2 C 4 F 9 ), LiC(SO 2 CF 3 ) 3 and the like.
  • the lithium salt one lithium salt selected from these may be used alone, or a mixture of two or more lithium salts selected from these may be used.
  • the concentration of the lithium salt is, for example, in the range from 0.5 to 2 mol/liter.
  • a polymer material containing a non-aqueous electrolyte can be used as the gel electrolyte. At least one selected from the group consisting of polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polymethyl methacrylate, and a polymer having an ethylene oxide bond may be used as the polymer material.
  • the cations constituting the ionic liquid include aliphatic chain quaternary salts such as tetraalkylammonium and tetraalkylphosphonium, fatty acids such as pyrrolidiniums, morpholiniums, imidazoliniums, tetrahydropyrimidiniums, piperaziniums, and piperidiniums. Nitrogen-containing heterocyclic aromatic cations such as cyclic ammoniums, pyridiniums, and imidazoliums may also be used.
  • the anions constituting the ionic liquid are PF 6 - , BF 4 - , SbF 6 - , AsF 6 - , SO 3 CF 3 - , N(SO 2 CF 3 ) 2 - , N(SO 2 C 2 F 5 ) 2 - , N( SO2CF3 ) ( SO2C4F9 ) - , C ( SO2CF3 ) 3- , etc. may be used .
  • the ionic liquid may contain a lithium salt.
  • At least one selected from the group consisting of the positive electrode active material layer 17, the electrolyte layer 13, and the negative electrode active material layer 11 may contain a binder for the purpose of improving adhesion between particles.
  • the binder is used to improve the binding properties of the materials constituting the electrode.
  • a binder polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polyacrylic acid methyl ester, polyacrylic acid ethyl ester, polyacrylic acid, etc.
  • Acrylic acid hexyl ester polymethacrylic acid, polymethacrylic acid methyl ester, polymethacrylic acid ethyl ester, polymethacrylic acid hexyl ester, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyether sulfone, hexafluoropolypropylene, styrene butadiene rubber, Examples include carboxymethylcellulose.
  • a copolymer of two or more selected materials can be used. Moreover, two or more selected from these may be mixed and used as a binder.
  • the battery 100 using the composite active material particles 30 can be manufactured, for example, by the following method.
  • the electrolyte layer 13 is formed by pressing the solid electrolyte powder.
  • a negative electrode material powder is placed on one side of the electrolyte layer 13 .
  • the negative electrode active material layer 11 is formed on the electrolyte layer 13 by pressurizing the negative electrode material powder.
  • the negative electrode material includes a plurality of composite active material particles 30 and a solid electrolyte 40.
  • the negative electrode material may include a conductive aid 50.
  • Powder of a positive electrode material is placed on the other side of the electrolyte layer 13.
  • the positive electrode active material layer 17 is formed by pressing the positive electrode material powder. Thereby, a power generation element including the negative electrode active material layer 11, the electrolyte layer 13, and the positive electrode active material layer 17 is obtained.
  • the battery 100 using the composite active material particles 30 can also be manufactured by a wet method.
  • a negative electrode slurry containing a plurality of composite active material particles 30 and solid electrolyte 40 is applied to a current collector to form a coating film.
  • the coating is passed through a roll or flat press heated to a temperature of 120° C. or higher and pressurized. Thereby, a negative electrode 210 is obtained.
  • Electrolyte layer 13 and positive electrode 220 are produced by a similar method.
  • the negative electrode 210, electrolyte layer 13, and positive electrode 220 are laminated in this order. Thereby, the battery 100 is obtained.
  • the battery 100 in this embodiment can be configured as a battery in various shapes such as a coin shape, a cylindrical shape, a square shape, a sheet shape, a button shape, a flat shape, and a stacked type.
  • Li 2 SP 2 S 5 powder may be simply referred to as "LPS”.
  • Si powder (3N, 2.5 ⁇ m pulverized product) was prepared as an active material.
  • Li 2 SiO 3 powder (2N, 10 ⁇ m pulverized product) was prepared.
  • Si powder and Li 2 SiO 3 powder were weighed so that the mass ratio of Si powder: Li 2 SiO 3 powder was 6:4. These were mixed in a glove box in an Ar atmosphere with a dew point of ⁇ 60° C. or lower to obtain a first mixed powder.
  • the first mixed powder was filled into a pod (made of SUS, volume: 45 mL) of a planetary ball mill (manufactured by Fritsche, P-7 type).
  • Li 2 SiO 3 powder was further added to the base particles so that the content ratio of Si in the final composite active material particles was 50% by mass to obtain a second mixed powder.
  • the second mixed powder was filled into a pod (made of SUS, volume 45 mL) of a planetary ball mill (manufactured by Fritsche, P-7 type). 40 g of zirconia balls (diameter 5 mm) were placed in the pod, the lid was closed, and the pod was treated at 400 rpm for 72 hours to coat the base particles. As a result, composite active material particles of Example 1 were obtained.
  • the composite active material particles of Example 1 had the structure described with reference to FIG.
  • powder of composite active material particles was pressure-molded with zinc powder (manufactured by Sigma-Aldrich) using a hydraulic cylinder (manufactured by Riken Kiki Co., Ltd.) at a pressure of 800 Mpa to produce pellets.
  • the cross section of the produced pellet was exposed using an ion milling device (ArBlade R5000, manufactured by Hitachi High Technologies).
  • the exposed cross section was observed using a scanning electron microscope (manufactured by Hitachi High-Technologies). Select any 10 composite active material particles included in the cross-sectional SEM image, and analyze the cross section of the selected 10 composite active material particles using an energy dispersive X-ray analyzer (manufactured by Oxford Instruments). Quantitative line scan was performed. From the obtained spectra, the elemental ratio of oxygen to silicon in the first region and the elemental ratio of oxygen to silicon in the second region were determined by the method described above. Specifically, first, for the cross section of each composite active material particle, the abundance ratio of oxygen and the abundance ratio of silicon are measured at five arbitrary points in the first region, the elemental ratio of oxygen to silicon is determined, and the average of these is determined.
  • the value was calculated. By dividing the sum of the calculated values by 10, which is the number of composite active material particles, the elemental ratio of oxygen to silicon in the first region was determined. Similarly, first, for the cross section of each composite active material particle, the abundance ratio of oxygen and the abundance ratio of silicon are measured at arbitrary five points in the second region, the elemental ratio of oxygen to silicon is determined, and the average value thereof is calculated. Calculated. By dividing the sum of the calculated values by 10, which is the number of composite active material particles, the elemental ratio of oxygen to silicon in the second region was determined.
  • Example 1 In the composite active material particles of Example 1, the elemental ratio of oxygen to silicon in the first region was 2, and the elemental ratio of oxygen to silicon in the second region was 1.2. This confirmed that in the composite active material particles of Example 1, more lithium silicate phase was contained in the first region located outside the second region. In addition, in Example 1, the same lithium silicate (Li 2 SiO 3 ) was used for the oxide phase (second oxide phase) of the base particle and the oxide phase (first oxide phase) of the coating layer. It was difficult to visually distinguish the second region from the first region in a cross-sectional SEM image.
  • Li 2 SiO 3 lithium silicate
  • LPS was used as the first solid electrolyte.
  • the composite active material particles of Example 1 and LPS were mixed at a mass ratio of 7:3 in a glove box in an Ar atmosphere with a dew point of ⁇ 60° C. or lower to obtain a mixture.
  • 10% by mass of VGCF-H (manufactured by Showa Denko) was added to the mixture and mixed. Thereby, the negative electrode material of Example 1 was obtained.
  • VGCF is a registered trademark of Showa Denko Co., Ltd.
  • Li(Ni 0.33 Co 0.33 Mn 0.33 )O 2 and LPS were mixed at a mass ratio of 7:3 in a glove box in an Ar atmosphere with a dew point of ⁇ 60° C. or lower. Thereby, a positive electrode material was obtained.
  • the positive electrode material is common to Examples and Comparative Examples.
  • Example 1 copper foil (thickness: 12 ⁇ m) was laminated on the negative electrode active material layer.
  • the negative electrode of Example 1 was obtained by press-molding these at a pressure of 360 MPa.
  • the negative electrode of Example 1 had the structure described with reference to FIG.
  • Example 1 was produced by sealing the insulating outer cylinder using an insulating ferrule to isolate the inside of the insulating outer cylinder from the outside atmosphere.
  • a battery of Comparative Example 1 was produced in the same manner as in Example 1, except that the negative electrode material of Comparative Example 1 was used in place of the negative electrode material of Example 1.
  • the battery was placed in a constant temperature bath at 25°C.
  • Constant current charging was performed at a current value of 770 ⁇ A, which is a 0.05 C rate (20 hour rate) with respect to the theoretical capacity of the battery, and charging was completed at a voltage of 4.2 V.
  • charging efficiency E was calculated as 100 ⁇ (charging capacity at 0.5C/charging capacity at 0.05C). The higher the value of charging efficiency E, the better the high-rate charging efficiency of the battery. The results are shown in Table 1.
  • the battery of Example 1 showed higher charging efficiency E than the battery of Comparative Example 1.
  • silicon particles expanded by charging are unevenly distributed inside the composite active material particles, and a lithium silicate phase that does not expand exists at the interface with the first solid electrolyte. It is thought that the deviation from the solid electrolyte was suppressed. It is considered that this improved the charging efficiency E because interfacial contact was maintained well during charging and insertion of lithium ions into the composite active material particles was not suppressed.
  • the charging efficiency E of the battery of Comparative Example 1 was lower than 50%.
  • many silicon particles were exposed on the outer surface of the composite active material particles, so the expansion and contraction of the silicon particles during charging and discharging promoted separation between the composite active material particles and the first solid electrolyte. It is thought that it was done. It is considered that this suppressed the insertion of lithium ions into the composite active material particles, resulting in a decrease in charging efficiency E.
  • the technology of the present disclosure is useful, for example, for lithium batteries such as all-solid lithium secondary batteries and non-aqueous electrolyte lithium ion batteries.

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WO2014148043A1 (ja) * 2013-03-22 2014-09-25 三洋電機株式会社 非水電解質二次電池
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WO2022044454A1 (ja) * 2020-08-27 2022-03-03 パナソニックＩｐマネジメント株式会社 非水電解質二次電池用負極材料および非水電解質二次電池

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